Preheat the oven to 350°F (175°C).
In a large skillet over medium heat, cook the breakfast sausage until browned, breaking it apart as it cooks (about 5-7 minutes).
Once the sausage is fully cooked, sprinkle flour over the sausage and mix well to combine. Cook for another 1-2 minutes.
Gradually whisk in the milk, stirring continuously until the mixture thickens (about 5 minutes). Add salt, black pepper, garlic powder, onion powder, and red pepper flakes, if using. Remove from heat.
Open the biscuit dough and separate the biscuits. Cut each biscuit into quarters.
In a 9x13-inch baking dish, spread the biscuit pieces evenly across the bottom.
Pour the sausage gravy mixture over the biscuit pieces, ensuring they are evenly coated.
If desired, sprinkle shredded cheddar cheese on top of the casserole.
Bake in the preheated oven for 25-30 minutes, or until the biscuits are golden brown and cooked through.
Remove from the oven and let it cool for a few minutes before serving.