The secret to these delicious mashed potatoes, obviously, is sugar.
2 pounds potatoes, washed and cut into 1-inch pieces
8 tablespoons (1 stick) unsalted butter, at room temperature
2 tablespoons whole milk
1 tablespoon sugar
2 teaspoons kosher salt
1 teaspoon black pepper
Fill a large pot with cold water, add the potatoes, bring to a boil over high heat, and boil until fork-tender, about 15 minutes.
Drain the potatoes and transfer to a bowl. Add the butter, milk, sugar, salt, and pepper and mash by hand. Serve hot.
For super-smooth potatoes, use a stand mixer fitted with the paddle attachment. Mix on medium until mashed together, about 2 minutes. Then mix on high just until light and fluffy, about 1 minute (longer will make black pepper–mashed potato glue, so be mindful of the time).