Preheat oven to 350.
Spray a 3 qt baking dish.
Brown sausage for 5 minutes over medium heat, crumbling as you brown.
Add onion. Continue cooking until sausage is thoroughly cooked and onion is translucent. Drain.
Put hash browns in medium bowl. Add sour cream, cheese, eggs, salt and pepper. Stir until combined. Add sausage/onion mixture. Stir again until combined.
Spoon mixture into 3 qt dish.
Add melted butter to cornflakes. Sprinkle cornflake/butter evenly over sausage hash brown mixture.
Bake at 350 for 45 minutes or until hot and bubbly.