Preheat oven at 350°F.
Cut up cabbage as you would for steaming. Put in a casserole dish.
In a separate bowl, combine cream of mushroom soup, mayonnaise and onion; pour over top of cabbage.
Mix together melted butter, Ritz crackers and cheese. Sprinkle over top of casserole.
Bake for about 30 minutes until bubbly and brown.
Submitted by: Kay Turner