Wash, peel and slice potatoes into quarters. In a saucepan cover potatoes with water and bring to a boil. Add 2 teaspoons salt to water and reduce heat to a simmer, continuing to cook until tender (about 40 minutes). Drain and return potatoes to saucepan, mash potatoes in the still-hot pan while adding chunks of the butter.

When the butter melts, stir in the dairy sour cream. Pour in the cream and milk; add salt and pepper to taste. Sprinkle with chopped chives and/or scallions, and optional cheese, if desired.