Garlic Mashed Potatoes

In a large pot of boiling salted water, cook potatoes and the 5 garlic cloves about 20 minutes or until tender when pierced with a fork; remove from heat and drain. Return potatoes to pot and stir over medium heat until excess moisture evaporates, about 1 minute. Remove from heat. Squeeze out the cloves from the cooled roasted garlic heads and add to the mashed potatoes with the other ingredients. Mash potatoes, garlic, and roasted garlic cloves with a potato masher until there are no lumps. Add butter, sour cream, and heavy cream; blend until well mixed. Season to taste with salt and pepper. Transfer to a serving bowl and serve.