Bring a pot of salted water to a boil.
While the water heats up, peel the potatoes and cut them into 1-inch chunks.
Carefully lower the potatoes into the boiling water. Cook over high heat, stirring occasionally, for about 12 minutes or until the potatoes are tender.
As soon as the potatoes are done cooking, drain them in a colander and return the empty pot to the stove over medium-low heat. Pour in the milk and butter. When the butter is completely melted, return the potatoes to the pot and add the salt, a few grinds of black pepper, the chives, and the lemon zest.
Mash with a potato masher or an electric hand mixer until the mashed potatoes are as smooth as you like them. If they seem too thick, drizzle in up to ¼ cup more whole milk and continue mashing. The potatoes will firm up a little more as they sit.
Serve hot with butter and/or gravy.