Preheat oven: Preheat oven to 350°F (175°C).
Prepare baking dish: Spray a 9×13 inch baking dish with nonstick cooking spray.
Cook beef and onion: In a large skillet, cook ground beef and diced onion until the meat is done.
Layer ingredients:
Add a layer of potatoes to the bottom of the baking dish.
Sprinkle with salt and pepper.
Top with a layer of meat mixture.
Sprinkle with a layer of shredded cheese.
Repeat layers twice more, ending with a layer of cheese.
Make soup mixture: In a bowl, combine cheddar cheese soup mix, evaporated milk, milk, and additional salt and pepper if desired.
Pour soup mixture: Pour the soup mixture over the layered ingredients.
Bake: Cover the baking dish tightly with aluminum foil and bake for 1 hour. Remove foil and bake for an additional 15 minutes to get a golden top.
Serve: Serve hot and enjoy!
Note: For thicker potatoes, you may need to bake for a longer time.