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Cheesy Sausage Breakfast Casserole

Overnight Cheesy Sausage Breakfast Casserole (Make-Ahead)

An easy, make-ahead casserole packed with savory breakfast sausage, sharp cheddar cheese, and soft cubed bread, soaked overnight in a rich milk and egg custard. Perfect for holiday brunch or easy weekend breakfasts.
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Prep Time 20 minutes
Cook Time 1 hour
Total Time 1 hour 20 minutes
Servings: 8 servings
Course: Breakfast, Brunch, Main Course
Cuisine: American, Comfort Food
Calories: 475
Ingredients Equipment Method Notes

Ingredients
  

Casserole Base
  • 1 pound bulk breakfast sausage (mild or spicy)
  • 6 slices day-old sandwich bread or Texas toast, cubed (about 4 cups)
  • 2 cups shredded cheddar cheese or a cheddar and Monterey Jack blend
  • Butter or cooking spray for greasing the dish
The Custard Mixture
  • 8 large eggs
  • 2 cups whole milk (or 2%)
  • 1 teaspoon dry ground mustard
  • 1/2 teaspoon salt
  • 1/4 teaspoon black pepper

Equipment

  • Large skillet
  • Mixing Bowl
  • 9x13 inch Casserole Dish

Method
 

Preparation Steps
  1. Prepare the Sausage: Crumble the breakfast sausage into a large skillet. Cook over medium heat until thoroughly browned, ensuring no pink remains. Drain off any excess grease completely and set the sausage aside to cool slightly.
  2. Prepare the Baking Dish: Preheat your oven to 350°F (175°C). Lightly grease a standard 9x13 inch casserole dish with butter or non-stick cooking spray.
  3. Arrange the Base Layers: Distribute the cubed bread evenly across the bottom of the prepared 9x13 inch casserole dish, ensuring the entire bottom is covered. Sprinkle the cooked and drained sausage evenly over the bread cubes. Finally, sprinkle the 2 cups of shredded cheese evenly over the top of the sausage and bread mixture.
Creating the Custard & Soaking
  1. Whisk the Wet Ingredients: In a separate large bowl, whisk the 8 large eggs vigorously until the yolks and whites are fully combined and slightly frothy. Pour in the 2 cups of milk.
  2. Add Seasoning: Add the 1 teaspoon of dry ground mustard, 1/2 teaspoon of salt, and 1/4 teaspoon of black pepper. Continue whisking until all the seasonings are dissolved and incorporated into the egg and milk mixture, forming the custard.
  3. Assemble and Soak: Carefully pour the entire custard mixture evenly over the sausage, bread, and cheese layers in the casserole dish. Gently press down on the bread cubes with a spatula or the back of a spoon to ensure they absorb the liquid thoroughly.
  4. Refrigerate (Crucial Step): Cover the casserole dish tightly with plastic wrap or aluminum foil. Place the casserole in the refrigerator and allow it to soak for a minimum of 4 hours, or ideally, overnight (up to 12 hours). This soaking time is essential for the bread to soften and hold the dish together.
Baking and Serving
  1. Pre-Bake Preparation: Remove the casserole from the refrigerator about 30 minutes before baking time to allow it to come slightly closer to room temperature. Remove the plastic wrap.
  2. Bake the Casserole: Place the uncovered casserole dish into the preheated 350°F (175°C) oven. Bake for 50 to 60 minutes.
  3. Check for Doneness: The casserole is done when the center is set, the eggs are no longer wet or jiggly, and the top is puffed and lightly golden brown. If the edges begin to brown too quickly, loosely tent the dish with aluminum foil for the remaining bake time.
  4. Rest and Serve: Remove the casserole from the oven and allow it to rest for 5 to 10 minutes before cutting into squares and serving immediately.

Notes

Using slightly stale or day-old bread is crucial, as it absorbs the custard better than fresh, soft bread. For a richer flavor, use heavy cream instead of whole milk. This casserole reheats well and can be stored covered in the refrigerator for up to 3 days.