Preheat oven to 350 degrees.
Pour frozen hash browns into a large bowl. Set aside.
In a medium bowl, with a spoon, stir together the onion, two soups, sour cream, cheese, and pepper.
Pour soup mixture over the potatoes and stir well.
Spray or coat baking dish with cooking spray or rub with oil.
Spread mixture into baking dish.
In a small bowl, add crushed corn flakes and melted butter. Stir. (You can use a blender or chopper, or place in a ziplock back and bang with a mallet or can until finely crushed.) Set aside.
Cover casserole with aluminum foil. Bake for 50 minutes.
Remove foil, sprinkle the corn flake mixture on top and continue baking uncovered an additional 10 minutes or until top is golden and bubbly.
Let cool for 15 minutes before serving.