Heat the oven to 350°F (175°C) and coat a 13x9-inch baking dish with nonstick spray.
Cook the sausage in a large skillet over medium heat until browned and no longer pink, breaking it into crumbles as it cooks. Drain any excess fat and set the sausage aside.
Cut each biscuit into four pieces. Arrange the pieces in a single, even layer across the bottom of the prepared baking dish.
Spread the cooked sausage over the biscuit layer, then scatter the shredded cheddar evenly on top.
Whisk the eggs and milk together in a bowl, season with salt and pepper, then pour the egg mixture evenly over the casserole layers.
Prepare the peppered gravy according to the package directions. Once ready, pour the gravy over the entire casserole, covering it evenly.
Bake in the preheated oven for 40 to 45 minutes, until the casserole is puffed and the top is golden brown. Allow to rest a few minutes before slicing and serving.