Cook macaroni according to package directions. Meanwhile, in a large skillet, cook the beef, mushrooms and onion over medium heat until meat is no longer pink; drain. Stir in the tomato sauce, pepperoni, olives, sugar, Italian seasoning and pepper.
Drain macaroni; add to meat mixture. Transfer to a 1-1/2-qt. baking dish coated with cooking spray. Sprinkle with cheeses.
Bake, uncovered, at 350° for 20-25 minutes or until heated through. Or before baking, cover and freeze casserole for up to 3 months.
To use frozen casserole: Thaw in the refrigerator overnight. Remove from the refrigerator 30 minutes before baking. Bake according to directions. Yield: 4 servings.