Hash Brown Potato Casserole

2 lb. frozen hash browns (thawed)
1/2 cup melted butter
2 cups sour cream
2 cups shredded cheddar cheese
1 tsp. salt
1 can of cream of chicken soup
1/2 tsp. pepper
1/2 cup onion chopped

Spread potatoes in casserole dish. Mix other ingredients together, and pour over potatoes. Bake at 350 for one hour.