Place 2 pounds halved baby gold potatoes, 1 ½ cups water, 1 cup whole milk, 1 stick unsalted butter, and 1 tablespoon kosher salt in a large pot or Dutch oven. Bring to a boil over medium-high heat.
Reduce the heat as needed to maintain a simmer. Cook, stirring occasionally, until the potatoes are knife-tender, about 15 minutes.
Turn off the heat. Use a wide spoon to skim off any white foam from the surface of the butter if desired. Garnish with finely chopped fresh parsley leaves if desired.
