Preheat the oven to 350°F (175°C) and grease a 9x13-inch baking dish.
In a large mixing bowl, combine hash browns, cream of chicken soup, sour cream, shredded cheese, melted butter, garlic powder, onion powder, salt, and pepper.
Spread the mixture evenly in the prepared baking dish.
In a small bowl, mix the crushed cornflakes with the additional melted butter.
Sprinkle the buttery cornflakes over the top of the potato mixture.
Bake for 45 minutes or until the top is golden brown and the casserole is bubbly.
Let it cool for a few minutes before serving. Enjoy!