pounds large Yukon Gold potatoes
Kosher salt and freshly ground black pepper
cup cold unsalted butter (2 sticks)
cup whole milk
tablespoon grated lemon zest (from 2 lemons)
- Peel the potatoes and cut them into 1 1/2- to 2-inch chunks. Place the potatoes in a large saucepan and add enough water to cover by 1 inch. Add 2 tablespoons salt, cover and bring to a boil over high.
- Uncover, lower the heat to a simmer and cook until the potatoes are very tender when pierced with a small paring knife, about 15 minutes. Drain and set aside.
- Meanwhile, cut the butter in 1/2-inch dice and put it back in the refrigerator.
- After the potatoes are drained, pour the milk into a small saucepan and heat over low just until it simmers. Turn off the heat.
- Place a food mill fitted with the finest blade on top of the large saucepan. Process the potatoes into the pan. (Alternately, use a ricer or potato masher, making sure the potatoes are very smooth before proceeding.)
- With the heat on low, vigorously whisk the cold butter into the potatoes several bits at a time, waiting for each addition to be incorporated before adding more butter.
- Once all the butter has been integrated, slowly whisk in enough of the hot milk to make the potatoes the desired consistency, creamy but still thick. Add 2 teaspoons salt and 1 teaspoon pepper. Whisk in the lemon zest, reserving some for garnish, if desired. Season to taste, and serve hot. Sprinkle with reserved lemon zest just before serving.