BROWN sausage; breaking up slightly while cooking. Place in a large saucepan with mushrooms and peppers. Stir in spaghetti sauce. Bring to a boil reduce heat and simmer 10 minutes. Add pasta to sauce.
SPOON 1/2 of the rigatoni mixture into a 13 x 9 inch (3.5 L) baking dish. Top with 1/2 of the cheeses; repeat layers.
BAKE at 375°F (190°C) for 20 minutes.