Preheat the oven to 350°F (175°C).
In a large mixing bowl, combine frozen hash browns, sour cream, cream of chicken soup, and melted butter.
Add chopped onion, salt, and pepper to the mixture.
Stir in 1 cup of shredded cheddar cheese, reserving 1 cup for topping.
Grease a 9x13 inch baking dish with cooking spray or butter.
Spread the hash brown mixture evenly in the prepared baking dish.
Sprinkle the reserved cheddar cheese on top.
Optional: add cooked bacon bits or diced ham for extra flavor.
Cover the dish with aluminum foil and bake for 30 minutes.
Remove the foil and bake for an additional 15 minutes or until golden brown and bubbly.