Preheat your oven to 350°F.
Grease a 9×13-inch baking dish for even baking.
Combine the hashbrowns, cheddar cheese, cream of chicken soup, sour cream, and chopped onions in a large bowl.
Stir well until thoroughly mixed.
Add the melted butter, salt, and black pepper to the mix.
Stir until all ingredients are evenly coated.
Transfer the mixture to the prepared baking dish and smooth the top.
Sprinkle the crushed corn flakes evenly over the top.
Place the dish in the preheated oven.
Bake for 30 minutes until bubbly and golden brown.