Brown sausage in skillet; Drain off any extra fat. Add green pepper,onion, mushrooms, Italian seasoning. Add garlic, cook 2 minutes, stir in tomato sauce and simmer, uncovered for 10 minutes. Top each muffin half with 2 T. meat sauce. Sprinkle with cheese. Broil until cheese melts and filling is hot. Serve at once. Makes 12 servings..