Heat oven to 350 degrees. Spray a 9x13 baking dish with no stick cooking spray. Heat water, butter, garlic and onion salts to boil in a large saucepan. Remove from heat. Add cream cheese, milk and sour cream, stirring until smooth. Stir in potatoes, mixing well. Spread into baking dish. Bake 1 hour or until golden brown. If desired, top with crumbled crisp bacon and cheddar cheese the last 15 minutes.
This can be made ahead and refrigerated for up to 48 hrs. before baking. This is a really good potato dish and sure beats peeling all those potatoes. I think it is just as good as a from scratch mashed potato casserole recipe I have.
