Preheat oven to 350°. Cook mostaccioli according to package directions. Meanwhile, in a large skillet, cook beef, green pepper and onion over medium heat until meat is no longer pink; drain. Stir in spaghetti sauce, soup, Italian seasoning and pepper., Drain mostaccioli. Add mostaccioli and 1-1/2 cups cheese to beef mixture. Transfer to two greased 11x7-in. baking dishes. Sprinkle with remaining cheese. , Cover and bake 20 minutes. Uncover; bake 5-10 minutes longer or until bubbly and cheese is melted. Freeze option: Cover and freeze unbaked casseroles up to 3 months. To use, thaw in refrigerator overnight. Remove from the refrigerator 30 minutes before baking. Preheat oven to 350°. Bake, covered, 50-60 minutes or until a thermometer reads 165°.