Brussels sprouts have suffered from a bad reputation for far too long, usually due to unfortunate encounters with boiled or steamed mushy versions of the vegetable. If you believe you hate Brussels sprouts, prepare to have your mind and your palate changed forever. The secret to transforming this humble green is twofold: high heat and, most importantly, a glorious, cheesy crust. We are talking about the intensely satisfying, crunchy, umami-rich perfection of Crispy Parmesan-Crusted Roasted Brussels Sprouts.
This recipe is not just about roasting; it is a dedicated technique focusing on creating a deeply caramelized, golden-brown armor on every single sprout half. By mixing finely grated Parmesan cheese with olive oil and spices into a thick paste and strategically placing the coated side face-down on a hot sheet pan, we force the cheese to fuse with the pan. This results in an irresistible, shatteringly crisp crust that elevates the usually boring side dish into the star of the plate. Forget soggy sprouts; prepare for a flavor explosion that will make even the most dedicated vegetable skeptic ask for seconds.
The entire process takes less than 45 minutes, making Crispy Parmesan-Crusted Roasted Brussels Sprouts the perfect accompaniment for weeknight dinners, holiday feasts, or even as a surprisingly addictive snack. Let’s dive into how you can master this crispy, cheesy vegetable perfection.
Why You’ll Love These Irresistible Crispy Parmesan-Crusted Roasted Brussels Sprouts
The difference between a good side dish and an unforgettable one often comes down to texture, and that’s precisely where these Crispy Parmesan-Crusted Roasted Brussels Sprouts shine. This isn’t just a simple toss-and-roast recipe; it’s engineered for maximum crunch and flavor. You’ll find countless reasons to make this recipe a permanent part of your weekly rotation.
The Texture Revolution: Say Goodbye to Mushy Sprouts
The number one complaint about Brussels sprouts is their tendency to become soft, watery, and sulfurous when cooked incorrectly. This recipe solves that problem definitively. Roasting at a high temperature (400°F/200°C) ensures rapid caramelization of the natural sugars in the sprout, creating slightly charred, smoky edges. But the real game-changer is the crust. The finely grated Parmesan melts quickly and then crisps up under the direct heat of the sheet pan, forming a solid, savory shell. When you scrape these off the pan, you get the satisfying sound of a genuinely crispy food, guaranteed.
A Flavor Bomb in Every Bite
Parmesan cheese provides a powerful punch of umami that deep, savory fifth taste which naturally balances the slight bitterness inherent in Brussels sprouts. We enhance this foundation with garlic powder, onion powder, and Italian seasoning, creating a robust, addictive flavor profile. The initial toss in olive oil and basic salt and pepper ensures the sprout itself is perfectly seasoned, while the cheese mixture adds a complex layer of garlicky, herby depth. The optional pinch of red pepper flakes cuts through the richness, offering a subtle warmth that keeps you coming back for more of these sensational Crispy Parmesan-Crusted Roasted Brussels Sprouts.
Simplicity Meets Sophistication
Despite the incredible results, the preparation is surprisingly straightforward. The key step is creating the Parmesan “paste,” which helps the cheese adhere securely to the vegetable, even during the high-heat roasting process. This small tweak eliminates the common issue of loose, burnt cheese crumbs floating around the pan. You spend just 15 minutes on prep, and the oven does the rest. This simplicity makes the Crispy Parmesan-Crusted Roasted Brussels Sprouts perfect for busy weeknights, yet the dramatic presentation and flavour make them sophisticated enough for any holiday table.
Versatility for Every Meal
These crispy delights pair well with virtually any main course. Serving a rich steak? The sprouts offer a necessary textural contrast. Preparing a comforting Slow Cooker Chili? They provide a fresh, green crunch. Even alongside light fish or poultry, they elevate the meal. They truly are the ideal, universally appealing side dish that manages to be both healthy and indulgently delicious thanks to that incredible Parmesan crust.
Why You Should Try This Recipe for Crispy Parmesan-Crusted Roasted Brussels Sprouts Today
If you are tired of the same old steamed green beans or plain roasted broccoli, this recipe offers a much-needed jolt of excitement to your vegetable routine. There are compelling reasons beyond just the amazing taste and texture why the Crispy Parmesan-Crusted Roasted Brussels Sprouts should be immediately added to your cooking repertoire.
Picky-Eater Approved Transformation
Brussels sprouts often appear on lists of least-favorite vegetables, but this recipe has proven to be the ultimate conversion tool. The rich, savory, and crispy Parmesan layer effectively masks any residual bitterness, making the sprouts highly palatable, even for children or adults who swore off them years ago. The goal is to make the sprouts taste less like a vegetable and more like a crunchy, cheese-forward snack. When presented with a side dish that boasts such a beautiful, golden crust, even the fussiest eaters are often willing to give these Crispy Parmesan-Crusted Roasted Brussels Sprouts a chance and they usually end up loving them.
Optimal Nutritional Retention through Roasting
Unlike boiling or steaming, which can leech water-soluble nutrients from vegetables, high-heat roasting helps retain more of the Brussels sprouts’ beneficial components. Roasting also concentrates the flavour, intensifying the natural sweetness and making the vegetable inherently more appealing. The slight charring adds a desirable smoky complexity that microwaving simply cannot replicate. By choosing this roasting method, you are maximizing both the health benefits and the flavour potential of the sprouts.
Perfecting the Art of Vegetable Roasting
Learning this specific technique for achieving a reliable, crispy crust opens the door to using this method on other vegetables. Once you understand how the Parmesan paste works and the critical importance of cut-side-down arrangement, you can apply it to things like cauliflower florets, asparagus spears, or even thick-cut potato wedges. Mastering the technique for these Crispy Parmesan-Crusted Roasted Brussels Sprouts gives you a new culinary skill that guarantees crisp results every time.
Quick and Minimal Cleanup
We all appreciate recipes that deliver maximum flavor with minimum hassle. Because this recipe relies on a single sheet pan lined with parchment paper, cleanup is incredibly fast. There is no need for multiple pots, strainers, or complicated saucing steps. Once the Brussels sprouts are tossed and coated, they go straight onto the pan. After enjoying your perfectly crispy side, you simply gather the parchment paper and throw it away making Crispy Parmesan-Crusted Roasted Brussels Sprouts a genuine win for convenience.
If you’re looking for other savory sides to complement your meals, consider exploring recipes like the Creamy Garlic Parmesan Pasta for a main course that pairs wonderfully with the robust flavors of these sprouts.
Ingredients and Essential Tools for Perfect Crispy Parmesan-Crusted Roasted Brussels Sprouts
Success in making these Crispy Parmesan-Crusted Roasted Brussels Sprouts hinges on using the right type of Parmesan and having a proper setup. Below is a detailed breakdown of the necessary ingredients and the utensils you’ll need to achieve that signature crunch.
The Mandatory Ingredient List
Ensure you measure accurately, as the ratios of oil and cheese are key to forming the perfect crust paste.
- 1.5 pounds Fresh Brussels sprouts: Look for firm, bright green sprouts without blemishes. Ensure they are trimmed and halved precisely.
- 4 tablespoons Olive Oil (divided): A good quality extra virgin olive oil or avocado oil works best for high-heat roasting. We divide this oil into two portions one for seasoning the sprouts and one for making the cheese paste.
- 1/2 teaspoon Kosher Salt: Used for initial seasoning. Kosher salt provides better texture and flavor coverage than standard table salt.
- 1/4 teaspoon Freshly Ground Black Pepper: Freshly ground offers superior aroma and bite.
- 1/2 teaspoon Garlic Powder: Essential for infusing robust, savory flavor into the cheese crust.
- 1/4 teaspoon Onion Powder: Works synergistically with the garlic powder to deepen the umami profile.
- 1/2 cup Finely Grated Parmesan Cheese: This is absolutely crucial. Do not substitute with shredded or shaved Parmesan, as it will not melt properly or form a consistent crust. It must be finely grated, like the texture of sand or fine sawdust.
- 1 tablespoon All-Purpose Flour (Optional): While optional, this simple addition acts as a binder, helping the cheese and oil emulsify into a thicker paste and ensuring better adhesion to the wet surface of the sprouts.
- 1 teaspoon Dried Italian Seasoning: Adds traditional aromatic herbs (like oregano, basil, thyme) that complement the Parmesan beautifully.
- A pinch of Red Pepper Flakes (Optional): For those who appreciate a touch of heat to cut through the richness.
The Critical Role of Finely Grated Parmesan
We cannot overstate the importance of using finely grated Parmesan cheese when making Crispy Parmesan-Crusted Roasted Brussels Sprouts. Shredded cheese contains higher moisture content and will melt and spread rather than fusing into a dense, solid crust. When the finely grated cheese is mixed with the olive oil, it creates a cohesive, thick paste. When this paste hits the hot baking sheet, it quickly caramelizes and hardens, forming the desired crisp texture. Using pre-grated Parmesan in a shaker bottle is acceptable, but if grating fresh cheese, ensure you use the finest setting on your microplane or box grater.
Choosing the Right Oil
For high-heat roasting at 400°F (200°C), you need an oil with a high smoke point. While standard extra virgin olive oil works for the seasoning toss, consider using a lighter-colored olive oil or avocado oil for the cheese paste portion if you are concerned about smoke. Avocado oil is nearly flavorless and has an excellent high smoke point, ensuring your crust browns perfectly without burning.
Necessary Kitchen Utensils and Tools
Having the right equipment ensures your roasting process is efficient and your cleanup is manageable.
- Large Sturdy Baking Sheet: Size matters! You need a standard half-sheet pan (13×18 inches). Using one that is too small will result in overcrowding, which creates steam. Steam is the enemy of crispiness.
- Parchment Paper or Aluminum Foil: Essential for preventing the Parmesan crust from sticking permanently to the pan. Parchment paper generally offers the best non-stick release for this type of cheesy crust.
- Two Large Mixing Bowls: One for the initial sprout seasoning and one dedicated to mixing the Parmesan paste.
- Sharp Knife and Cutting Board: For trimming and halving the Brussels sprouts accurately.
- Thin, Sturdy Metal Spatula: This is a key tool for Step 8. A thin, stiff metal spatula is necessary to cleanly scrape and lift the sprouts without leaving the cheese crust behind on the pan.
- Measuring Spoons and Cups: Precision in seasoning ratios is important for consistent flavor.
By gathering these specific ingredients and tools, you are setting yourself up for success in creating the most delicious Crispy Parmesan-Crusted Roasted Brussels Sprouts you have ever tasted.
Detailed Step-by-Step Instructions: Mastering the Crispy Parmesan-Crusted Roasted Brussels Sprouts Technique
Follow these instructions closely, paying special attention to the preparation of the cheese paste and the arrangement on the pan, as these two steps are the keys to achieving that signature crispy crust.
Step 1: Preheat the Oven and Prepare the Pan
Preheat your oven to 400°F (200°C). High heat is mandatory for achieving crispness and proper caramelization. Line a large, sturdy baking sheet (a half-sheet pan is ideal) with parchment paper or heavy-duty aluminum foil. If using foil, lightly grease it with a small amount of cooking spray or olive oil, as cheese sometimes adheres more strongly to foil than to parchment. The goal is a non-stick surface. Crucially, ensure the baking sheet is large enough so that the Brussels sprouts can be spread in a single, non-overlapping layer. Overcrowding steams the vegetables instead of roasting them, ruining the crispness.
Step 2: Prepare and Clean the Brussels Sprouts
Wash the Brussels sprouts thoroughly under cold running water. Inspect them and remove any loose, damaged, or yellowed outer leaves. Using a sharp knife, trim the tough, woody ends of the stems. Then, cut every single Brussels sprout in half lengthwise. When halving, try your best to keep the root end mostly intact; this prevents the individual leaves from detaching and burning during the high-heat roasting process.
Step 3: Initial Oil and Seasoning Coating
Transfer the trimmed and halved Brussels sprouts into a large mixing bowl. Add 2 tablespoons of the olive oil (reserving the remaining 2 tablespoons for the cheese crust). Sprinkle in the kosher salt and black pepper. Toss vigorously use your hands for the best results until every piece is lightly and evenly coated in the oil and seasoning. This foundational seasoning ensures the core flavor of the sprout is delicious even before the cheese crust is added.
Step 4: Create the Parmesan Crust Mixture
In a separate, small bowl, combine the remaining ingredients: the 1/2 cup of finely grated Parmesan cheese, the remaining 2 tablespoons of olive oil, garlic powder, onion powder, dried Italian seasoning, and the optional red pepper flakes. If you are using the flour for added binding, stir it into this mixture now. Mix thoroughly until the ingredients form a thick, cohesive, somewhat paste-like mixture. The consistency should be spreadable but not runny it should look like thick mud or a dense pesto. This consistency is essential for securing the cheese to the sprout.
Step 5: Coat the Sprouts with the Crust Mixture
Add the prepared Parmesan crust mixture directly to the bowl containing the seasoned Brussels sprouts. Use your hands or a rubber spatula to carefully mix and coat each sprout half evenly. The most important part of this step is ensuring that the flat, cut sides of the sprouts are heavily coated with the cheese mixture. This is the surface that will be in direct contact with the pan and form the signature Crispy Parmesan-Crusted Roasted Brussels Sprouts.
Step 6: Arrange and Roast the Sprouts
Transfer the coated Brussels sprouts to the prepared baking sheet. This step is critical: Arrange them in a single, even layer, and position every single sprout so that the cut side the side coated with the most cheese is facing DOWN against the parchment paper. This direct contact is necessary for the cheese to melt and crisp into a solid, golden crust. If the sprout is rounded-side down, the cheese will simply melt onto the rounded top and drip off, preventing the formation of the desired crust.
Step 7: The First Roasting Interval
Place the baking sheet in the preheated 400°F (200°C) oven and roast for the first 12 to 15 minutes. Do not disturb or move the sprouts during this period. Do not open the oven door unless absolutely necessary. The cheese needs uninterrupted time in contact with the hot surface to fully melt, bubble, and then crisp up into the crust. You should be able to smell the savory, browning Parmesan.
Step 8: The Flip and Finishing Touches
After the initial roasting interval, carefully remove the baking sheet from the oven. Using a thin, sturdy metal spatula, gently scrape under the sprouts. The cheese crust should be firmly attached and browned. Gently flip each sprout over so the crispy, rounded side is now facing down. If the crust is sticking slightly, use the spatula to pry it up gently, ensuring the crispy cheese remains attached to the sprout and does not flake off onto the pan. Return the sprouts to the oven and roast for an additional 8 to 10 minutes. This second roast interval finishes tenderizing the center of the sprout and slightly chars the rounded edges, resulting in the perfect Crispy Parmesan-Crusted Roasted Brussels Sprouts.
Step 9: Serve Immediately
The Brussels sprouts are ready when they are tender when pierced with a fork, and the outer leaves are nicely charred. Remove the baking sheet from the oven. Use your spatula to scrape the remaining crispy pieces of Parmesan crust off the sheet and mix them in with the sprouts. Transfer immediately to a serving dish. These Crispy Parmesan-Crusted Roasted Brussels Sprouts are best enjoyed hot while the crust is at its absolute crispiest. Serve them alongside your favorite main dishes, perhaps even complementing a decadent dessert like Chewy Pecan Pie Cookies.
Tips, Variations, and Avoiding Common Mistakes for Crispy Parmesan-Crusted Roasted Brussels Sprouts
While the recipe is straightforward, a few expert tips can ensure your Crispy Parmesan-Crusted Roasted Brussels Sprouts turn out restaurant-quality every time. Understanding common pitfalls and exploring simple variations will allow you to tailor this side dish to any preference.
Avoiding the Three Biggest Mistakes
- Do Not Overcrowd the Pan: This is the single greatest enemy of crispiness. If your sprouts are layered or touching too much, the trapped moisture will create steam instead of allowing the heat to directly brown the surface. Always use a large enough sheet pan to ensure adequate space between the sprouts. If necessary, use two baking sheets.
- Stick to Finely Grated Cheese: As emphasized, shredded cheese (the thick strands) will melt into a puddle and burn, rather than forming a cohesive crust. Always use finely grated (powdered or microplaned) Parmesan for success.
- Resist the Urge to Peek or Flip Too Early: The first 12–15 minutes are dedicated to creating the crust-to-pan bond. If you move the sprouts prematurely, the melting cheese will stick to the paper/foil instead of fusing to the sprout, resulting in a separated, messy crust. Be patient!
Flavor Variations to Try
The base recipe for Crispy Parmesan-Crusted Roasted Brussels Sprouts is versatile and can be adapted to different cuisines and palates:
- Add Heat: Instead of simple red pepper flakes, try a pinch of smoked paprika or a quarter teaspoon of cayenne pepper in the crust mixture for a deeper, smokier heat. A drizzle of hot honey after roasting provides a sweet-spicy finish.
- Lemon Finish: After removing the sprouts from the oven, toss them lightly with the zest of half a lemon. The bright citrus flavor offers a fantastic contrast to the rich Parmesan crust.
- Herb Swap: If you don’t have Italian seasoning, try fresh herbs added at the end. A tablespoon of finely chopped fresh parsley or a mixture of thyme and rosemary adds an earthy complexity.
- Balsamic Glaze: Roast the sprouts as directed, then, immediately upon serving, drizzle a homemade or store-bought balsamic glaze over the top. The tanginess balances the richness perfectly.
Dietary Adaptations
- Vegan/Dairy-Free Crispy Parmesan-Crusted Roasted Brussels Sprouts: The cheese is the main challenge here. Substitute the Parmesan cheese with a high-quality nutritional yeast blend or a specific vegan Parmesan product (often cashew-based). Nutritional yeast provides that classic savory, cheesy flavor (umami), and when mixed with oil and flour, it can form a surprisingly effective, crispy crust.
- Gluten-Free: This recipe is naturally gluten-free if you omit the optional flour binder. The oil and cheese mixture will still adhere well enough, though the crust might be slightly less uniform. If you want to use a binder, substitute the all-purpose flour with a gluten-free all-purpose blend or rice flour.
Serving Suggestions
While these sprouts are a phenomenal side, they can also be used in other applications:
- Appetizer: Serve with toothpicks and a side of creamy ranch or aioli for dipping.
- Salad Topper: Chop the cooled Crispy Parmesan-Crusted Roasted Brussels Sprouts and use them as a savory, crunchy topping for a large grain or green salad instead of croutons.
- Bowl Base: Use them as the vegetable base for a power bowl, topped with quinoa, grilled chicken, and a light vinaigrette.
For more delicious and unique vegetable preparations, including holiday sides and seasonal baking ideas, be sure to visit and Follow me on Pinterest for more easy side dish recipes!
Nutritional Value and Health Benefits of Crispy Parmesan-Crusted Roasted Brussels Sprouts
While the addition of cheese and oil certainly makes these Crispy Parmesan-Crusted Roasted Brussels Sprouts taste decadent, they remain a side dish packed with significant health benefits. It’s an excellent way to introduce essential nutrients into your diet in a highly palatable form.
Brussels Sprouts: A Nutritional Powerhouse
Brussels sprouts belong to the cruciferous family, alongside broccoli and cabbage, and are exceptionally nutrient-dense. A standard serving (about one cup, raw) offers:
- Vitamin K: Brussels sprouts are one of the best plant sources of Vitamin K, essential for blood clotting and bone health.
- Vitamin C: High in Vitamin C, they support the immune system and act as a powerful antioxidant, helping to fight free radicals.
- Fiber: They are a great source of dietary fiber, promoting digestive health, regularity, and helping to manage blood sugar levels. The fiber content helps the roasted sprouts feel satisfying and filling.
- Antioxidants: They contain several antioxidants which have been linked to reducing the risk of chronic diseases.
Roasting, especially at high heat, slightly lowers the Vitamin C content, but the overall nutritional profile remains strong. Crucially, by roasting them correctly, we avoid the bitter compounds that are often released during extended boiling, making them taste much sweeter and more appealing.
The Role of Healthy Fats (Olive Oil)
The olive oil used in the coating is primarily composed of monounsaturated fats. These fats are considered heart-healthy and can help lower bad cholesterol (LDL) levels. Furthermore, the fat content is essential because many of the vitamins in Brussels sprouts, such as Vitamin K, are fat-soluble. Consuming them with a healthy fat like olive oil dramatically improves the body’s ability to absorb these nutrients.
Understanding the Parmesan Addition
The Parmesan cheese adds delicious flavor and structure but also contributes to the calorie and fat count. Parmesan is a rich source of calcium and protein. The quantities used in the recipe (1/2 cup spread across 4 servings) are moderate. Each serving will likely contain:
- Calories: Approximately 200–250 calories per serving (depending on the exact size of the sprouts and oil used).
- Protein: A good boost of protein (around 8–10 grams per serving), largely from the Parmesan cheese and the vegetable itself.
- Fats: Primarily healthy fats from the olive oil (around 15–20 grams), crucial for the crispy crust.
- Carbohydrates: Low in net carbs, high in fiber.
Compared to other common side dishes that might rely on heavy creams or starches, these Crispy Parmesan-Crusted Roasted Brussels Sprouts offer an excellent balance of flavor, texture, and powerful nutritional benefits, making them a side dish you can feel great about serving frequently.
For another great vegetarian side that’s packed with flavor, try this Stuffed Baked Acorn Squash.
Frequently Asked Questions (FAQ) about Crispy Parmesan-Crusted Roasted Brussels Sprouts
What is the secret to getting the cheese to stick and form a crust on the Crispy Parmesan-Crusted Roasted Brussels Sprouts?
The secret lies in two specific techniques. First, you must use finely grated Parmesan cheese mixed with olive oil to create a thick paste that adheres better than dry seasonings. Second, you must arrange the sprouts cut-side down against the hot pan during the first roasting interval. This direct contact with the heat allows the cheese to melt, fuse, and then crisp up into a solid, golden crust.
Can I use shredded Parmesan cheese instead of finely grated for this recipe?
No, using shredded Parmesan is highly discouraged for the best results. Shredded cheese has higher moisture content and will simply melt and spread out on the pan before burning, failing to form the desired cohesive crust. Fine grating is necessary to create the paste-like consistency needed for the ultimate Crispy Parmesan-Crusted Roasted Brussels Sprouts.
How do I prevent my Brussels sprouts from becoming soggy during roasting?
To prevent sogginess, you must use high heat (400°F) and avoid overcrowding the baking sheet. Overcrowding traps steam, which softens the vegetables. Ensure the sprouts are spread in a single layer with space around them, allowing the moisture to evaporate quickly and the surfaces to caramelize properly.
Can I prepare the Crispy Parmesan-Crusted Roasted Brussels Sprouts ahead of time?
While you can trim and halve the sprouts a day ahead and store them in the fridge, the cheese coating should be applied right before roasting. The oil and cheese paste works best when freshly mixed. For reheating, spread leftovers on a sheet pan and bake at 350°F for about 5–7 minutes until crisp again; microwaving will make them soggy.
What oil is best for roasting Brussels sprouts at 400°F?
Oils with high smoke points are best for 400°F roasting. Avocado oil is an excellent neutral choice, but standard olive oil (not extra virgin, which has a lower smoke point) or a blend works well. The goal is an oil that facilitates the high-heat crisping without burning prematurely.
Conclusion: Your New Favorite Crispy Parmesan-Crusted Roasted Brussels Sprouts Recipe
You now hold the definitive guide to creating the most incredible side dish you could imagine: Crispy Parmesan-Crusted Roasted Brussels Sprouts. This recipe is a testament to the power of proper technique. By focusing on high heat, utilizing the binding properties of a fine Parmesan paste, and mastering the crucial cut-side-down arrangement, we transform a historically challenging vegetable into a golden, cheesy, crunchy delight. No more limp, watery sprouts only deeply savory, tender-on-the-inside, and shatteringly crispy-on-the-outside perfection.
Whether you’re looking for a simple, yet impressive addition to a holiday meal or just trying to sneak more healthy, fiber-rich vegetables onto your weeknight plate, this recipe delivers on all fronts. It’s fast, requires minimal cleanup, and is almost universally loved. We’ve covered everything from the critical ingredient choices like why finely grated Parmesan is non-negotiable to expert tips on avoiding overcrowding to ensure maximum crunch.
We encourage you to try this recipe for Crispy Parmesan-Crusted Roasted Brussels Sprouts tonight. Share the joy of truly crispy roasted vegetables with your family and friends, and prepare to convert even the most skeptical eaters. If you make these delicious sprouts, we would love to hear about your experience! Please leave a comment below with your favorite variation or serving suggestion, and don’t forget to share this recipe with anyone who still believes they “hate” Brussels sprouts. Happy roasting!

CRISPY PARMESAN-CRUSTED ROASTED BRUSSELS SPROUTS
Ingredients
Equipment
Method
- Preheat your oven to 400°F (200°C). Line a large, sturdy baking sheet with parchment paper or aluminum foil for easy cleanup. If using foil, lightly grease it with cooking spray or oil. Ensure the baking sheet is large enough so the sprouts can be spread in a single layer.
- Wash the Brussels sprouts thoroughly. Remove any loose or damaged outer leaves. Trim the tough ends of the stems, then cut the sprouts in half lengthwise, from the top down through the root end. Try to keep the root end intact to prevent the leaves from separating during roasting.
- In a large mixing bowl, toss the trimmed and halved Brussels sprouts with 2 tablespoons of the olive oil. Add the kosher salt and black pepper, and toss vigorously until every piece is lightly coated. This initial coating ensures the basic flavor is integrated.
- In a separate, small bowl, create the Parmesan crust mixture: Combine the finely grated Parmesan cheese, the remaining 2 tablespoons of olive oil, garlic powder, onion powder, dried Italian seasoning, and the optional red pepper flakes. If using, stir the all-purpose flour into this cheese mixture now. The resulting consistency should be a thick, somewhat paste-like mixture.
- Add the Parmesan crust mixture directly to the bowl containing the seasoned Brussels sprouts. Use your hands or a rubber spatula to carefully mix and coat each sprout half evenly. Ensure that the cut sides of the sprouts are heavily coated with the cheese mixture, as this is the side that forms the crust.
- Transfer the coated Brussels sprouts to the prepared baking sheet. It is crucial to arrange them in a single, even layer, positioned so that the cut side (the side coated with the cheese) is facing down against the baking sheet. This direct contact is essential for developing the deep, golden, crispy crust.
- Place the baking sheet in the preheated 400°F (200°C) oven and roast for 12 to 15 minutes without disturbing them. Do not open the oven door during this period; the cheese needs time to melt and crisp onto the pan. You should start to smell the cheese browning.
- After the initial roasting interval, carefully remove the baking sheet. Using a thin, sturdy metal spatula, gently scrape under the sprouts and flip them over so the rounded side is now facing down. If the crust is sticking, gently pry it up, ensuring the crispy cheese remains attached to the sprout. Return the sprouts to the oven and roast for an additional 8 to 10 minutes, or until the sprouts are fork-tender and the edges of the green leaves are slightly charred.
- Remove the baking sheet from the oven. Scrape any remaining crispy pieces of Parmesan crust off the sheet and mix them in with the sprouts. Serve immediately while they are hot and the crust is at its crispiest.