Place sausage in a medium, heavy-bottomed skillet. Break apart with a large wooden spoon and cook over medium heat until it crumbles and is no longer pink, about 3-5 minutes. Remove from skillet with a slotted spoon into a bowl and set aside. Remove all drippings except for about 1 tablespoon from the skillet.
Whisk in flour into the hot sausage drippings over medium heat until they are smooth.
Whisk the milk into the flour mixture in the skillet, whisking constantly until thickened, about 5-7 minutes. Stir in the reserved sausage, salt and pepper.