In a large mixing bowl combine onion, sour cream, soup, cheese, salt and pepper. Press the excess water out of the hash browns and then add them to the soup mixture and mix well.
Transfer to a 9x12 inch casserole dish.
Sprinkle potato chips on top, then drizzle with butter.
Bake in preheated oven for 45 minutes to 1 hour, until golden brown.
