Preheat oven to 400-F degrees. Brown the ground chuck and onion and then drain off excess fat. Stir in the ketchup, salt, pepper, and hash brown potatoes. Place in a greased 10-inch pie plate and top with the cheddar cheese.
In a medium bowl, mix the remaining ingredients. (It will look lumpy.) Pour over the ground beef and cheese. Bake for about 30 minutes or until set. Let it stand about 5 minutes before slicing.