1. Combine mashed potatoes, cream cheese, sour cream, milk, onion salt, and pepper to taste. Mix well and place in a large casserole.
2. Cover and bake at 325 degrees F (165 degrees C) for 50 minutes.
OR…
After assembling, put them in crock pot dish and refrigerate overnight. Reheat in the crock pot for several hours with a few pats of butter on top