Preheat and Prep:
Preheat your oven to 375°F (190°C) and grease a 9x13-inch baking dish.
Quarter the biscuits and set them aside.
Cook the Sausage:
Heat a large skillet over medium heat and cook the sausage until browned and crumbled. Do not drain all the grease; leave about 1 tablespoon in the skillet.
Make the Gravy:
Sprinkle the flour over the cooked sausage and stir until the sausage is coated.
Slowly pour in the milk, whisking constantly to prevent lumps.
Add garlic powder, onion powder, black pepper, and red pepper flakes (if using). Cook the gravy, stirring frequently, until thickened, about 5-7 minutes. Adjust seasoning to taste.
Assemble the Casserole:
Spread half of the quartered biscuits on the bottom of the prepared baking dish.
Pour the sausage gravy evenly over the biscuits.
Top with the remaining biscuits, spreading them out across the casserole.
Bake:
Bake in the preheated oven for 20-25 minutes, or until the biscuits are golden brown and cooked through.
Optional: Sprinkle cheddar cheese on top during the last 5 minutes of baking for an extra cheesy layer.
Serve:
Let the casserole cool for 5 minutes before serving. Serve warm and enjoy!