Rinse the potatoes really well under hot water and scrub until the potatoes are clean. On a cutting board, cut the potatoes into one or two inch pieces. Fill a soup pot up with water and add the potato pieces to the water. Bring the water to a boil. Boil until potatoes are fork tender. Drain all of the water from the potatoes (be careful, the water will be hot). With an electric mixer or a potato masher, mash the potatoes until they are no longer any large chunks present. Once the potatoes are mostly smooth (some small clumps are okay), add the whipping cream (milk), butter, sour cream, garlic cloves, salt, and pepper. If you want to serve the potatoes with some parsley, garnish with chopped fresh or dried parsley on top.