Cook noodles according to package directions, set aside.

Fry sausage and onions in large skillet, draining grease.

Stir in spaghetti sauce, mushrooms, black olives and Italian seasoning, heat through.

Coat inside of 5-quart slow cooker with cooking spray, spread 1/3 of the meat sauce, cover with 1/3 of the noodles, 1/3 of the pepperoni and 1/3 of the cheeses. Repeat two more times.

Cover and cook on low 3 to 4 hours until heated through and cheese is melted.