Preheat oven to 350 F. Lightly grease a 9x13-inch baking dish with non-stick cooking spray.
In a large bowl, combine the sour cream, cream of mushroom soup, melted butter, spicy brown mustard, garlic powder, onion powder and 1 cup of the shredded sharp cheddar cheese. Stir in the frozen potatoes and mix well.
Transfer the cheesy potatoes into the prepared baking dish and sprinkle the remaining cheese over the top.
Bake in the preheated oven for 45 to 50 minutes, or until potatoes have softened.
Serve as holiday breakfast side dish or holiday feast side dish.
NOTE: If you wish to you hash brown style potatoes, you can do that in place of the diced potatoes and reduce the cooking time to 35 minutes.