Cook on high 3-4 hours or low 6-7 hours, stirring every hour or so or until tender.
Using a hand masher, mash potatoes until smooth. Stir in butter, sour cream, parsley and cream cheese if using. Season with salt & pepper to taste.
Serve or keep on warm until serving.
(Nutrition information provided is an estimate and will vary based on cooking methods and brands of ingredients used.)