Preheat your oven to 350°F (175°C).
In a large mixing bowl, combine frozen hash browns, melted butter, and onion.
Spread the hash brown mixture evenly in a greased 9x13 inch baking dish.
In a separate bowl, whisk together sour cream, cream of chicken soup, and shredded cheese.
Pour the creamy mixture over the hash browns, spreading evenly.
Sprinkle additional cheese on top for extra flavor.
Season with salt, pepper, and your choice of herbs.
Bake in the preheated oven for 45 minutes, until golden brown and bubbly.
Allow to cool slightly before serving.
Garnish with chopped green onions if desired.