1. Saute onions and peppers in oil and butter until limp. Add tomatoes and simmer 30 minutes. Cook spaghetti according to package directions. Toss with oil and set aside. Preheat oven to 325 degrees. Make a cream sauce by melting butter and stirring in flour until smooth and bubbly. Gradually stir in milk and cream stirring until thickened. Add cheese, stirring until cheese melts. Set aside. Toss spaghetti, mushrooms, olives and tomato sauce together and place in baking dish. Cover with cream sauce and bake 45 minutes.