2 lbs. frozen hashbrowns, thawed
1/4 c. chopped onion
2 (10 3/4 oz.) cans cream of potato soup
1 pt. sour cream
10 oz. med. sharp Cheddar, grated
1/2 c. Parmesan cheese

Mix potatoes, onion, soup, sour cream and grated cheese. Place into greased 9 x 13 inch casserole dish and sprinkle with Parmesan. Bake uncovered 55 minutes at 350 degrees.