1 lb. sweet Italian sausage
1/2 c. chopped onion
3 c. (8 oz.) sm. rigatoni, uncooked
1 c. Ricotta cheese
3 1/2 c. (32 oz. jar) spaghetti sauce
2 c. (8 oz.) shredded Mozzarella cheese
3 tbsp. grated Parmesan cheese

Saute sausage in medium skillet until well browned on all sides. Remove from pan, slice into thin pieces. Return to pan and add onions. Saute until onions are tender but not brown. Cook small rigatoni for 10 minutes; drain. Combine rigatoni, sausage mixture and ricotta mixture well. Pour 1/2 cup sauce on bottom of 3 quart casserole. Spread 1/3 of rigatoni and sausage mixture over sauce, cover with 1 cup sauce. Sprinkle 3/4 cup Mozzarella and 1 tablespoon Parmesan cheese over sauce. Repeat layers of rigatoni and sausage mixture, sauce, Mozzarella and Parmesan twice, ending with Parmesan cheese. Cover and bake at 400 degrees for 20 to 30 minutes. 4 to 6 servings.