Cheesy Potatoes

1 large bag of frozen hash brown potatoes
1 - 16 ounce container sour cream
1 can of cream of mushroom soup
1 - 8 oz. shredded cheddar cheese plus 4 to 8 ozs. more to put on top
6 tbsp. of butter or margarine
garlic powder

Thaw out the hash brown potatoes and put in a large bowl.  On stove top melt the butter or margarine in medium pan.  Add sour cream and soup.  Mix together until well blended and heated through.  Add this mixture to the hash browns in the bowl.  Add the 8 oz. of cheese, sprinkle some garlic powder in and mix all together real thoroughly.   Put in  9 by 13 inch pan.  Sprinkle the top with the rest of the cheese.  Cover the pan with foil.  Bake for approximately 1 and 1/2 to 2 hours at 400 degrees until potatoes are fully done.