Easy Au gratin Potatoes

This recipe is a favorite of mine when I have company over, doesn't take much time, and I can just throw it in the oven which is always nice.

• 2/3 bag frozen southwest style hash browns
• 4 oz shredded cheddar or colby cheese
• 1/2 cup onion (chopped small)
• 1 can cream of chicken soup
• 1-1/2 cup sour cream
• 4 Tbsp butter or margarine
• cornflakes

Combine sour cream and cream of chicken soup.  Add potatoes, cheese and onion.  Mix well.  Poor mixture into greased casserole dish.  Crush cornflakes and spread over potato mixture.  Melt butter or margarine and pour over cornflakes.  Bake at 350 for 1 to 1-1/4  hours.  (make sure middle is hot)