Cook Potatoes by baking or boiling. You can either bake the potatoes or peel, chop and boil them until soft and tender. (My aunt does baked. I like to, but to sometimes save on time, I boil them)
In a large saucepan, over medium heat, melt butter. Once butter is melted add flour. Stir to make a roux and let it simmer while stirring for a minute.
Slowly add milk and half and half. Stir constantly until thickened. This can take a while but be patient, it will.
Stir in salt, pepper, onion powder and garlic salt.
Stir in small diced and tender potatoes along with the sour cream until evenly mixed through.
Put in a crock pot and keep on warm until ready to serve.
I like to serve mine with bread bowls. Also, in separate bowls, I put cheese, cooked and crumbled bacon, and green onions so that people can add how much they want of what.