Preheat oven to 375 degrees F.
Mash warm baked potatoes or boiled potatoes with a potato masher. Add butter, cream cheese and sour cream. Mash while adding milk/cream a little at a time until to reach a creamy consistency.
Stir in remaining ingredients (except toppings) and spread into a 2 quart casserole dish.
(Nutrition information provided is an estimate and will vary based on cooking methods and brands of ingredients used.)