Buttermilk's rich, creamy flavor means you can skip adding extra butter to this easy recipe.
Peel and quarter potatoes. Cook, covered, in boiling salted water, 20 to 25 minutes or until tender; drain.
Meanwhile, in small saucepan combine buttermilk, butter, salt, and pepper. Heat over low heat until just warm, stirring frequently (do not boil).
Transfer potatoes to mixing bowl; mash with potato masher or beat with mixer on low speed. Slowly add buttermilk mixture, mashing until smooth. Makes 6 side-dish servings.