Preheat oven according to cake mix instructions. Prepare cake batter as directed on the box, using eggs, oil, and water.

Pour batter into a greased 9x13 inch baking pan and bake until a wooden skewer inserted into the center comes out clean.

Let the cake cool completely in the pan before proceeding.

In a medium bowl, whisk together the chocolate pudding mix, milk, and vanilla extract until smooth and creamy.

Once the cake is cool, poke holes all over the top using a wooden skewer or the handle of a wooden spoon. Don't poke all the way through.

Slowly pour the pudding mixture over the poked cake, allowing it to seep into the holes. Let it sit for at least 30 minutes to absorb.

Frost the cake with the chocolate frosting. If the frosting is too thick, add a little milk to thin it out.

Create tombstones by breaking chocolate sandwich cookies in half. Melt green candy melts and spread around the base of the cake for grass. Melt white candy melts and write RIP on the tombstones using a toothpick. Add gummy worms (optional). Refrigerate for at least 30 minutes before serving.