• 4 lb large yellow-fleshed potatoes ,peeled and quartered
• 1 3/4 cups half-and-half
• 3/4 stick (6 tablespoons) unsalted butter, cut into tablespoon pieces
• 1/2 teaspoons salt
• 1/2 teaspoon black pepper
• 1/4 cup drained bottled horseradish
• Cover potatoes with salted cold water by 2 inches in a 5-quart heavy pot, then simmer, uncovered, until very tender, about 25 minutes.
• While potatoes are simmering, bring half-and-half, butter, salt, and pepper just to a simmer, stirring until butter is melted. Keep hot, covered.
• Drain potatoes in a colander, then immediately force through ricer into a large bowl.
• Stir in hot milk mixture, then horseradish.