3 1/2 pounds red potatoes, washed well and quartered
1 stick butter, cut into pieces
3 shallots, minced
1 cup whole milk
Freshly ground pepper
1/4 cup sour cream
2 cups shredded extra-sharp white Cheddar (7 ounces)
Add the potatoes to a large pot and cover with cold water. Add a large pinch of salt. Bring to a boil, reduce to a simmer, and cook until tender, about 25 minutes. Drain well in a colander.
Add the butter, shallot and milk to the same pot the potatoes were cooked in and heat until the butter is melted and hot; season well with salt and pepper. Remove from the heat.
Add the potatoes to the hot milk and butter mixture. Add the sour cream. Using a potato masher, mash the potatoes until semi-smooth. Add the cheese and stir until the cheese is incorporated. Adjust the seasoning as necessary.