Peel the potatoes and rinse. Cut the potatoes in half or quarters depending on the size.
5 pounds potatoes
Place potatoes in a large dutch oven or stock pot. Cover potatoes with cold, salted water. The water should cover the potatoes by at least one inch.
Bring the water to a boil and cook just until the potatoes are fork tender, about 15 minutes. Drain the potatoes and return to the hot pot.
While the potatoes are cooking, start heating the milk and heavy cream in a small sauce pan over low heat OR heat in the microwave.
¾ cup whole milk, ½ cup heavy cream
Allow the potatoes to sit in the pot for about 5 minutes so any additional moisture can evaporate.
Add softened butter to the potatoes and mash until desired consistency is reached.
12 tablespoons butter
Add in the hot milk and cream a little at a time mashing until your desired consistency is achieved. You don't need to use all of the milk or cream.
Finally, stir in the sour cream (or cream cheese) and add salt and pepper to taste.
¼ cup sour cream, salt and pepper to taste