This baked potato casserole is perfect for prepping a day or two before a holiday or dinner party. Simply follow all of the steps up until the point of baking. Then cover with a layer of plastic wrap so that it touches the top of the casserole and squeeze out all of the air pockets and place the casserole in the fridge. You want to cover the casserole so that it is airtight. This way the potatoes don't oxidize and turn brown. About an hour and 15 minutes before you want to eat, take the casserole out of the fridge and put it in the oven. (It will need to bake for an extra 10-15 minutes since it will be cold from the fridge.)