Place potatoes and garlic in heavy medium pot. Cover potatoes with water. Add 1 teaspoon salt. Bring to boil over high heat. Reduce heat to medium; cover and simmer until potatoes are tender when pierced with skewer, about 25 minutes.
Drain. Return potatoes and garlic to pot. Add whipping cream and butter. Using potato masher, mash until well blended. Season to taste with salt and pepper.