In a medium saucepan, cook sausage over medium heat until brown, using a wooden spoon to break up meat as it cooks. Add butter to saucepan. Stir until butter is melted. Stir in flour, pepper, and salt. Cook and stir for 1 minute. Whisk in milk. Cook and stir until thickened and bubbly. Cook and stir for 1 minute more.
Split 4 Cheddar Biscuits. Serve sausage mixture over split biscuits. If desired, garnish with fresh sage.