1Place the potatoes in a large saucepan and add water to cover. Heat to boiling. Reduce heat and simmer over medium heat until tender. Drain.
2Place the potatoes in a mixing bowl. Cut the butter and cream cheese into pieces and add to the potatoes. Beat with an electric mixer until light and fluffy. Add the sour cream. Season to taste.
3Serve immediately or reheat in a buttered casserole at 300 degrees for 20 minutes.