Preheat oven to 450.
In a Large mixing bowl, combine the hashbrowns, onion, shredded cheeses, salt and pepper.
Add soup and mix thoroughly.
Add melted butter and mix thoroughly.
Grease a 9X13 pan with additional butter.
Transfer the hashbrown mixture into greased pan and spread evenly. .
Bake for 1 hour until golden brown.
Rotate pan for even browning if necessary.
Let stand for 5 minutes before serving.
