Set your oven to preheat at 350°F (175°C), and lightly grease a 13x9-inch baking dish.
Cook the sausage in a skillet over medium heat, crumbling as it browns. Once fully cooked, drain off any excess fat.
Chop each biscuit into roughly 1-inch sections and scatter them across the base of the prepared baking dish in a single, even layer.
Distribute the cooked sausage over the biscuit pieces.
Sprinkle the shredded cheese evenly across the sausage layer.
In a mixing bowl, beat the eggs with the milk until smooth, then season with salt and pepper. Gently pour this egg mixture over the layered ingredients in the baking dish.
Prepare the gravy according to the directions on the package, resulting in about 2 cups. Once thickened, pour the hot gravy over the entire casserole.
Transfer the dish to the oven and bake for 35 to 45 minutes, or until the biscuits are golden and the eggs have set fully.
Serve hot. Leftovers can be stored and reheated easily.