Hands down the best-ever make-ahead recipe for mashed potatoes. Do not be afraid to serve these at Thanksgiving or Christmas, they are even better than regular mashed potatoes, and it's one less vegetable side to have to worry about at the last minute. Make up to 24 hours ahead and refrigerate. Or make even further in advance, and freeze.
You can use up to 5 pounds (2 kg) of potatoes. If you do, increase the milk a bit more. Use a chopped herb such as chive or parsley. Dried is fine, or omit altogether. Don't even think about the fat content in this dish! But if you do, you can reduce it marginally by using lower-fat cream cheese and sour cream, and skim milk.