Baked Spaghetti - With ground meat

1 cup chopped onion 1 cup chopped green pepper 1 tablespoon margarine 28 ounces diced tomatoes with juice 1 (10 ounce) can sliced mushrooms 1 (14 ounce) can[...]

1 lb lean ground beef (browned) 1 cup onion 1/2 cup sweet red pepper, chopped 1/2 cup green pepper , chopped 4 -6 garlic cloves , minced 1 tablespoon butter 2[...]