Preheat oven to 350°F; grease a 9x13-inch baking dish.

Thaw 1 bag (30 oz) frozen shredded hash browns; squeeze out as much moisture as possible with a clean kitchen towel.

Mix dry hash browns, 1 can (10.5 oz) cream of chicken soup, 2 cups sour cream, 2 cups shredded sharp cheddar, ½ cup melted butter, ½ cup diced onion, 1 teaspoon garlic powder, 1/2 teaspoon salt, and ½ teaspoon black pepper in a large bowl.

Spread the mixture evenly in the prepared baking dish.

Reserve the remaining 1 cup of cheese for topping (3 cups total in the recipe).

Bake uncovered for 45 minutes.

Remove from oven; sprinkle reserved cheese evenly over top.

Increase oven to 425°F; bake casserole another 12-15 minutes until top is golden brown and edges crispy. Center should reach 165°F.

Rest 5-10 minutes before serving.

Serve as a side or main with eggs on top.