5 pounds potatoes, peeled and quartered
6 ounces cream cheese
1 cup sour cream
2 teaspoons onion salt
1 teaspoon salt
1/4 teaspoon pepper
2 tablespoons butter

Boil potatoes until tender. Combine all ingredients and whip in mixer until smooth. Place in greased casserole. Dot with butter and bake in 350 oven 30 minutes until heated through. 

Can be made ahead of time and refrigerated.