Preheat oven to 350° Fahrenheit. Spray 9x13-inch baking dish with nonstick cooking spray.
Combine hash browns, cream of chicken soup, cheese, sour cream, onion, salt, pepper, and ½ cup melted butter in a large mixing bowl. Pour potato mixture into prepared baking dish.
Corn Flake Topping
Crush Corn Flakes until the total volume is equal to 2 cups. Combine crushed cornflakes with ¼ cup melted butter.
Spread buttery Corn Flakes over the top of the potato casserole and bake in the preheated oven for 45 minutes to 1 hour.
Top with diced chives or green onions, if desired.
Video
Notes
If you are going to use frozen hash browns, be sure to thaw them overnight in the refrigerator prior to using them.Do you like to mix things up? Instead of a crushed Cornflake topping, crush two sleeves of Ritz crackers and toss with ½ melted butter and use as you would the Cornflake topping.