Saute 1/4 cup onion in 1/2 stick melted butter or margarine. In a very large mixing bowl, combine sauteed onion, 32 oz. frozen hash brown potatoes, 10 3/4 oz. cream of chicken soup, 8 oz. Cheez Whiz, and 8 oz. sour cream. Add salt and pepper to taste Mix thoroughly with a large spoon. Melt 1/2 stick margarine, and add 2 cups cornflakes. Heat the cornflakes, until they are crispy and the margarine is absorbed. Do not over-brown the cornflakes!

Spray a 13-inch by 9-inch by 2-inch Pyrex dish (or similar oven-proof dish) with cooking oil spray. Spoon the casserole mixture into the baking dish, and smooth it out with the back of the spoon. Sprinkle the crisp cornflakes evenly over the top. Bake for 40 to 45 minutes in an oven that has been preheated to 350 degrees. Remove from the oven, and serve while hot! For me, this is a hearty casserole, and a wonderful comfort food.