2 1/2 pounds red potatoes 2 1/2 pounds idaho potatoes 1 1/4 cup butter 1 1/4 cup creamy pureed horseradish 1 1/2 cup heavy cream 2 1/2 teaspoons kosher salt 1 1/2 teaspoon ground fresh black pepper
Wash potatoes well, leaving the skins on. Cut the potatoes in half lengthwise. Place in a kettle and fill with enough water to cover potatoes. Bring to a boil, reduce heat and simmer until potatoes are very tender.
Drain well and add butter while potatoes are hot. Begin to hand mash. Add all remaining ingredients and mash well leaving them just slightly lumpy.