Baked Potato Casserole

5 pounds potatoes, mashed (do not add milk or butter)
6 oz cream cheese, softened
1 cup sour cream
2 tsp onion salt
1 tsp salt
1/4 tsp pepper
2 Tbsp butter
Grated cheddar cheese

Mix potatoes with cream cheese, sour cream, salts and pepper. Pour into large casserole. Dot with butter and sprinkle top with grated cheese. Bake at 350F for 35-45 minutes. Serves 12.

This recipe can be made ahead and refrigerated until needed, however, it needs quite a bit longer time to warm through when chilled.