Take hashbrowns out of the freezer and allow to thaw slightly. Just enough so you can mix in with other ingredients.

Preheat oven to 350 degrees. Spray a 13 x 9 casserole dish with non-stick cooking spray.

While hashbrowns are thawing, grate 2 cups cheddar cheese—Reserve 1 cup for the top.

In a large bowl, combine soup, sour cream, salt, pepper, garlic powder, and 1 cup of shredded cheese. Stir well. Add potatoes and onion. Stir until well combined. 

Pour mixture into a 13 x 9-inch well-greased casserole dish. Top with the remaining 1 cup of cheese. Drizzle melted butter over the top of the casserole. 

Bake at 350 degrees for about an hour or until golden brown. **Some ovens cook differently. I usually start checking around 50 minutes and continue to cook for up to an hour.