Crock Pot Pizza


1 1/2 lb. hamburger, browned and drained 
16 oz (or more) shredded Mozzarella cheese 
1 chopped onion 
1 pkg. sliced pepperoni 
2/3 box rigatoni noodles, cooked 
1 can cream of mushroom soup 
1 can mushrooms 
2 jars pizza sauce 

Alternate layers in crockpot as follows: hamburger,
noodles, cheese, soup, mushrooms, onions, sauce and
pepperoni. Heat 4 hours on low in crock pot.