Creating the Cheesy Hashbrown Casserole is simple when you follow these easy steps:

1. Preheat the Oven: Preheat your oven to 350°F (175°C) and grease a 9×13-inch baking dish.
2. Mix the Base: In a large bowl, combine the thawed hashbrowns, sour cream, cream of chicken soup, melted butter, chopped onion (if using), garlic powder, salt, and black pepper. Stir until well mixed.
3. Add Cheese: Fold in 1 1/2 cups of shredded cheddar cheese into the mixture.
4. Transfer to Baking Dish: Pour the hashbrown mixture into the greased baking dish, spreading it evenly.
5. Top with Cornflakes: If using, sprinkle crushed cornflakes over the top for added crunch.
6. Add Remaining Cheese: Sprinkle the remaining 1/2 cup of shredded cheese on top of the cornflakes.
7. Bake: Place the casserole in the preheated oven and bake for 45 minutes, or until it’s bubbly and the top is golden brown.
8. Cool Slightly: Remove from the oven and allow to cool for a few minutes before serving.

Following these steps ensures that your Cheesy Hashbrown Casserole turns out perfectly every time.