Cook and drain pasta. In a large skillet, brown Italian sausage then drain off fat. Add green pepper, onion, mushrooms and red pepper flakes and cook 5 minutes. Add black olives and pepperoni. Stir in spaghetti sauce. Add mixture to cooked pasta. Place in a large casserole dish sprayed with cooking spray. Top with shredded cheese and bake for 35-40 minutes until hot and bubbly. Serve with garlic bread or bread sticks.