Place potatoes in a saucepan and cover with cold water by 1 inch. Add salt. Bring to a boil, then reduce heat to a simmer. Cover the pan and cook until potatoes are tender, about 15 minutes.
While potatoes are cooking, heat butter and milk in a separate saucepan.
When potatoes are cooked, drain them and mash with a vegetable masher. Put potatoes through a potato ricer. Return riced potatoes to the saucepan and add the butter-milk mixture, salt, and pepper. Whip the potatoes to incorporate the liquid. Taste and adjust seasoning.
Transfer mashed potatoes to a serving bowl, top with chives and serve immediately.
YIELD: 4 servings I PREP TIME: 15 min COOK TIME: 20 min I TOTAL TIME: 35 min