Set out frozen potatoes for about an hour before cooking to start thawing. (Or microwave for a few minutes)

Heat oven to 350

Mix sour cream and soup in a bowl.

Fold in butter and 1 1/2 cups cheese.

Add potatoes and mix until covered.

Salt and pepper to taste. Stir again.

Dump mixture into sprayed 9x13 casserole

Add remaining cheese on top.

Bake for one hour or until bubbly on edges and cheese on top starts to brown.

If you're adding a crunchy topping, I wouldn't add it until the last 20 minutes to avoid over browning.