Peel And Quarter Potatoes. Cook In Boiling Salted Water In Medium-Size Saucepan Until Tender, Drain. Mash, Adding 1 T Butter And The Pepper. Add Sour Cream, Horseradish, And Minced Parsley. Whip As For Mashed Potatoes. Place In Serving Bowl; Top With 1 T Melted Butter And Serve.