Preheat the Oven: Set your oven to 350°F (175°C) and grease a large 9×13-inch baking dish with butter or nonstick spray.
Mix the Base: In a large mixing bowl, combine the thawed (or partially thawed) hash browns, cream of chicken soup, sour cream, 1 stick of melted butter, shredded cheddar cheese, and diced onion if using. Stir well until everything is evenly coated and creamy.
Season: Add garlic powder, Tony’s seasoning, salt, and pepper to taste. Adjust the seasoning as needed to your personal preference — these flavors will deepen as the dish bakes.
Transfer to Baking Dish: Pour the mixture into the prepared baking dish, spreading it evenly with a spatula so it cooks consistently throughout.
Bake: Place the dish in the oven and bake uncovered for about 1 hour, or until the potatoes are tender and bubbling around the edges. The cheese should be fully melted and the top lightly golden.
Slow Cooker Option: For a hands-off version, grease your crockpot and cook the mixture on low for 5–6 hours, stirring once or twice during cooking if possible.
