Cook sausage in a large skillet over medium-high heat, stirring with a spatula and breaking sausage apart as it cooks, 5 to 7 minutes. Stir in onion powder, garlic powder, bouillon granules, and black pepper until well combined and sausage fully cooked, 5 to 7 minutes more.

Stir in flour until mixture coated, then stir in milk and bring to a boil. Reduce heat to a simmer; stir until thickened, 5 to 7 minutes. Taste; adjust seasonings. Set aside.

Preheat the oven to 350 degrees F (175 degrees C). Grease a 9x13-inch baking dish with butter; set aside.

Cut each biscuit into four pieces. Arrange 1/2 biscuits in bottom of the prepared baking dish; cover with sausage-gravy mixture. Top with remaining 1/2 biscuits.

Bake in the preheated oven until biscuits are fully cooked and golden brown, 13 to 15 minutes.

Set aside before serving for 3 to 5 minutes.