Peel the potatoes and cut in half. In a medium saucepan of salted boiling water, cook the potatoes until fork-tender, about 40 minutes. Drain the potatoes well and return them to the saucepan. Cook over low heat for 1 minute, tossing, to evaporate remaining moisture. Meanwhile, melt the butter in a saucepan. Add the cream and heat until just warm. Using a potato ricer, mash the potatoes and garlic in the saucepan until they are broken up. Stir in cream and butter mixture. Season with salt and pepper to taste.