Preheat oven to 350 degrees and grease a 9x13 baking dish.
Mix together the hashrbowns, 1 1/2 cups cheddar, sour cream, cream of chicken soup, melted butter, onions, garlic powder, onion powder, and salt and pepper in a medium bowl.
Spread the mixture into a 9x13 baking dish and sprinkle the remaining cheddar over the top.
Bake uncovered for 45 minutes.
Package sizes are shrinking and 32 ounce bags of frozen hashbrowns can be harder to find these days. I often use a 26 ounce bag with no other changes and it works just fine.Sometimes we add a cup of crumbled bacon to these cheesy potatoes for extra goodness!