1Heat 1 inch water to boiling in 3-quart saucepan. Add potatoes. Heat to boiling; reduce heat to low. Cook about 15 minutes or until tender; drain. Return potatoes to saucepan. Shake pan with potatoes over low heat to dry; remove from heat.
2Mash potatoes until no lumps remain. Beat in yogurt, horseradish and salt. Add milk in small amounts, beating after each addition (amount of milk needed to make potatoes smooth and fluffy depends on the kind of potatoes used). Beat vigorously until potatoes are light and fluffy. Sprinkle with parsley.