Preheat the oven to 350°F. Lightly grease a 9×13 inch baking dish, and set aside.
In a large bowl, mix together the hashbrowns and ½ cup butter. Add in the pepper, salt, onion, soup, sour cream and cheese, and mix until fully incorporated. Pour the mixture into the prepared baking dish.
In a small bowl, mix together the remaining ¼ cup butter with the cornflakes. Sprinkle on top of the hashbrown mixture.