Preheat oven to 350.
Cook mostaccioli according to package directions.
Coarsely chop bell pepper and onion.
Cook and stir ground beef, bell pepper, and onion over medium heat 10-12 minutes or until beef is no longer pink; drain.
Stir in seasoning. Add spaghetti sauce and soup; mix well.
Combine mostaccioli, meat sauce and 1 1/2 cups of cheese in a baking dish.
Bake 35 minutes.
Sprinkle with the remaining 1/2 cup cheese. Bake uncovered 10 minutes or until thourgouhly heated.