Preheat oven to 350F. Thinly slice 4 medium sized potatoes and layer into a 9x9 or 2 quart baking dish. After each layer of potatoes add salt and pepper. Shred about 1-2 cups cheddar cheese and layer on top of potatoes.
In a mixing bowl add 1/2 cup uncooked oats, 3/4 cup milk, 1 small chopped onion, 1/4 cup ketchup, 1 egg, 1 lb. ground beef (raw) and salt and pepper to taste.
Mix well and add the meat mixture onto the cheese layer. Bake for 1 hour and 20 minutes or until the top is nicely browned and bubbling and the potatoes are cooked through.