Put the potatoes in a large saucepan and cover by an inch with cold water. Add 1-1/2 tsp. kosher salt. Bring to a simmer over medium heat, partially cover, and simmer until the potatoes are tender and easily pierced with a skewer, about 20 minutes. Drain, and return the potatoes to the saucepan. Put the pan over low heat, and shake or stir the potatoes until a floury film forms on the bottom of the pot, 1 to 2 minutes.
Using a ricer, food mill, or potato masher, mash the potatoes. Stir in the butter, 1 piece at a time, with a broad wooden spoon. Once the butter is thoroughly absorbed, add the buttermilk in three parts, stirring vigorously between additions. Add the chives, and season to taste with salt and pepper. Serve hot.
Make Ahead Tips
If you need to keep the potatoes warm before serving, create a makeshift double-boiler: Transfer the potatoes to a large stainlesssteel bowl, cover tightly with plastic wrap, and place the bowl over a pan of simmering water. The potatoes can be held for about an hour this way—just be sure that the bottom of the bowl sits above the surface of the water and that the water doesn’t simmer away.
nutrition information (per serving):
based on six servings;
Photo: Scott Phillips