1 box rigatoni
1 sm. onion
1/2 c. butter
1 can cream of mushroom soup
2 cans tomatoes
2 c. Mozzarella cheese
1/4 lb. American cheese

Cook rigatoni according to directions; drain and rinse. Chop and saute onion in butter. Combine onions, cream of mushroom soup, and tomatoes. In 13 x 9 inch pan, put in layers - rigatoni, botha cheese and sauce mixture. Bake at 350 degrees for approximately 1 hour.