Peel all potatoes (unless intentionally leaving "new potato" skins in the recipe) and chop in half.
Cover potatoes with cold water in a large pot on the stovetop, and boil over medium heat until very fork tender (15-20 minutes), then drain. (Note: undercooking will result in lumps in your finished dish.)
Using a hand potato masher, roughly mash the potatoes .
Add remaining ingredients to mashed potatoes.
With an electric hand mixer, mix thoroughly until potatoes are smooth and creamy.
Spoon mashed potatoes into a glass or ceramic serving dish. They may be served at this point, or else stored covered in the fridge for 24-48 hours, then reheated and served.
If making this recipe 1-2 days in advance, be sure to store in the fridge tightly covered (I recommend both plastic wrap + the glass lid). To serve, remove plastic wrap (keep glass lid on) and heat at 300F for 45min, or until thoroughly heated.
To enhance presentation, I recommended serving with a small pat of butter on top of the warm potatoes, with a sprinkle of dried parsley flakes.
Substitutions are not recommended for this recipe as each ingredient is distinctive in the overall flavour profile.
Freezer-safe with good results if you have too many leftovers.