Cook the pork sausage in a small skillet over medium heat until no longer pink, 3 to 5 minutes, breaking it into crumbles with a spoon as it cooks. Drain any excess grease.

Add the butter to the skillet and heat until melted. Sprinkle in the flour, salt, and pepper, stirring constantly until the mixture is smooth and well combined.

Gradually pour in the milk while stirring constantly. Bring the mixture to a boil and continue stirring until the gravy thickens, about 2 minutes.

Split the warm biscuits in half, place on plates, and ladle the hot sausage gravy generously over the top. Serve immediately with extra black pepper if desired.