Separate The Garlic Cloves and remove their papery husks. Slice each clove into halves or, if large, thirds. Peel the potatoes (unless they are newly harvested), quarter them and slice thinly. Put the garlic, potatoes, parsley and butter in a small sauce- pan, add water to cover by 2 inches and lightly salt. Bring to a boil, lower the heat, and simmer, partially covered, until the potatoes and garlic are soft and the water has cooked away, about 25 minutes. Pass the potatoes and garlic through a food mill. Don't use a food processor or blender as it will give the puree a gooey, unpleasant texture. If you don't have a food mill, mash the potatoes by hand, then work them through a strainer for a smooth texture or leave it a little rough and irregular. Stir in the milk or cream and additional butter, if desired. Add salt to taste and season with pepper.