Peel the potatoes and cut into 1/2-inch pieces. Combine with the milk, garlic and cold water to cover in a medium saucepan. Bring to a boil and reduce the heat. Simmer, covered, for 25 minutes or until the potatoes are very tender.
Drain, reserving 1/4 cup cooking liquid. Return the potatoes and garlic to the saucepan and add the cream and butter. Mash until smooth, adding a small amount of the reserved liquid if necessary for the desired consistency. Season with salt and pepper.