Place sausage in a large, deep skillet. Cook over medium heat until evenly brown. Drain on paper towels, reserving 2 tablespoons fat in skillet. Stir in flour, salt, and pepper. Cook, stirring constantly, until flour is brown. Add chopped green onion, and cook until tender. Gradually stir in milk, and cook until thickened. Add more milk if necessary to achieve preferred consistency. Serve with sausage.