9 lg. potatoes, peeled, cut into lg. chunks
1 c. sour cream
6 oz. cream cheese, softened
1/2 c. milk
3 tsp. onion salt
Salt & freshly ground pepper
8 tbsp. butter, softened

Boil potatoes until tender; drain. Using electric mixer, mash potatoes in large bowl. Mix in sour cream, cream cheese, 5 tablespoons of softened butter, milk and seasonings. Place in a lightly buttered 9 x 14 inch oval baking dish. Preheat oven to 400 degrees. Slice remaining butter (3 tablespoons) on top of potatoes. Bake until heated through a lightly browned, about 30 minutes.

Can be made 2 days ahead. Cover and refrigerate.