Ingredients
4 pounds russet potatoes (6 to 7), peeled and cut into 1 1/2-inch pieces
Kosher salt and freshly ground pepper
6 tablespoons unsalted butter, plus more, melted, for serving (optional)
1 cup heavy cream
1 cup sour cream
Chopped chives, for serving
Preparation
In a large pot, cover potatoes with at least 2 inches of water. Bring to a boil, then season generously with salt. Continue boiling until potatoes are tender and easily pierced with the tip of a knife, 10 to 12 minutes. Reserve 1 cup cooking liquid, then drain potatoes and let them cool and steam a few minutes in colander.
Meanwhile, return pot to medium heat; add butter. When it melts, add heavy cream and bring to a simmer. Remove from heat. Rice potatoes into pot (or return them to pot and mash with a potato masher until creamy).
Add sour cream and stir until smooth; season to taste. If necessary, add reserved potato-cooking liquid, 1/4 cup at a time, until you reach desired consistency. Serve, topped with melted butter and chives.
