Preheat oven to 350°F (175°C). Grease a 9x13-inch baking dish.
In a large bowl, combine thawed hash browns, 1/2 cup melted butter, cream of chicken soup, sour cream, chopped onion, 1 1/2 cups cheddar cheese, salt, and pepper. Mix well.
Spread the mixture evenly into the prepared baking dish.
In a small bowl, mix crushed corn flakes with 1/4 cup melted butter. Sprinkle over the hash brown mixture.
Top with remaining 1/2 cup cheddar cheese.
Bake uncovered for 45-50 minutes, until bubbly and golden brown on top.
Let rest for 5 minutes before serving.
Tips
For a crispier topping, bake an additional 5-10 minutes.
Can be assembled the night before and refrigerated; add 10 minutes to baking time.
Substitute cream of mushroom soup for a different flavor.