Melt 2 tablespoons butter in frying pan and add 1 onion, cut up small and brown. Add 1 can mushrooms, drained, saute together. Add about 3 or 4 squash cut up (unpeeled); add to onion and mushrooms and simmer until squash is done, but not mushy. Put in baking dish and sprinkle grated sharp cheese over top and bake in a slow oven about 30 minutes. This can be fixed the day before and then just warm up in oven. Salt and pepper to taste.