Cook spaghetti according to package directions (minus 2 minutes so the pasta isn't mushy since we're baking it, too). Meanwhile, in a Dutch oven, cook the beef, green pepper and onion over medium heat until meat is no longer pink; drain. Stir in the tomato sauce, pepperoni, mushrooms, olives and seasonings. Drain spaghetti. Spoon 1 cup meat mixture into each of two greased 13-in. x 9-in. baking dishes. Layer with spaghetti and remaining meat mixture. Sprinkle with cheeses. Cover and freeze one casserole for up to 3 months. Bake the remaining casserole, uncovered, at 350° for 20-25 minutes or until heated through. Make bagged salad. To use frozen casserole: Thaw in the refrigerator overnight. Remove from the refrigerator 30 minutes before baking. Cover and bake at 350° for 40 minutes. Uncover; bake 5-10 minutes longer or until cheese is melted.