Creating Hashbrown Chicken Casserole is a simple and enjoyable process. Follow these steps to produce an amazing dish:

1. Preheat Oven: Preheat your oven to 350°F (175°C).
2. Prepare Baking Dish: Grease a 9×13-inch baking dish with cooking spray or butter.
3. Mix Base Ingredients: In a large bowl, combine cream of chicken soup, sour cream, milk, garlic powder, and black pepper. Stir until well blended.
4. Add Chicken: Fold in the shredded chicken and diced onion until evenly coated with the mixture.
5. Incorporate Hashbrowns: Add the thawed hashbrowns to the mix, combining everything thoroughly.
6. Transfer to Baking Dish: Spread the mixture evenly in the prepared baking dish.
7. Add Cheese: Sprinkle the shredded cheddar cheese generously over the top.
8. Bake: Place the dish in the preheated oven and bake for 45-50 minutes, or until the top is bubbly and golden.
9. Optional Topping: If using, sprinkle crispy fried onions on top during the last 10 minutes of baking for added crunch.
10. Garnish and Serve: Once baked, remove from the oven. Garnish with fresh parsley before serving.

Following these steps will help you make an incredible Hashbrown Chicken Casserole with minimal effort.