1. Grease a 9×13 inch baking dish with the butter or nonstick spray, coating the bottom and sides well.

2. In a large skillet over medium heat, cook the breakfast sausage, breaking it into crumbles, until browned and no pink remains, then drain off excess grease.

3. Add the diced onion, red bell pepper, and green bell pepper to the same skillet and sauté for 4–5 minutes until just softened and lightly golden.

4. Cut each refrigerated biscuit into 6–8 bite-size pieces and scatter them evenly over the bottom of the prepared baking dish.

5. Sprinkle the cooked sausage evenly over the biscuit pieces, followed by the sautéed peppers and onions, then top with most of the shredded cheddar cheese, reserving a small handful.

6. In a large mixing bowl, whisk together the eggs, whole milk, kosher salt, black pepper, garlic powder, smoked paprika, and crushed red pepper flakes until smooth and well combined.

7. Slowly pour the egg mixture over the biscuit, sausage, and veggie layers, gently pressing down any pieces that float so everything is moistened.

8. Sprinkle the remaining cheddar cheese evenly over the top of the casserole.

9. Cover the dish tightly with plastic wrap or foil and refrigerate for at least 2 hours or up to overnight to let the biscuits soak in the custard.

10. When ready to bake, remove the casserole from the refrigerator and let it sit at room temperature while you preheat the oven to 350°F (175°C).

11. Uncover the dish and bake for 40–50 minutes, or until the eggs are set in the center and the top is puffed and deeply golden.

12. Let the casserole rest for 10 minutes before slicing into squares and serving warm.