Place the potatoes in a pot of cold, salted water and bring to a boil over medium heat. Reduce the heat to a simmer and cook for 20 to 25 minutes, or until the potatoes are fork tender.

Drain well and then pass the potatoes through a ricer or food mill into a mixing bowl.

In a small saucepan, heat the heavy cream and butter together over low heat until the butter is melted. Stir in the sour cream and mix well. Add the warm cream mixture to the potatoes in small increments until the consistency is smooth and creamy. Stir in the chives and season with salt and pepper.