Preheat your oven to 350°F (175°C).

In a skillet, heat olive oil over medium heat. Cook the ground beef and onion, seasoning with salt and pepper, until the meat is browned.

In a large mixing bowl, combine the sliced potatoes, cooked beef mixture, cream of mushroom soup, and milk. Mix well.

Spread the mixture into a greased 9x13 inch baking dish.

Cover the dish with aluminum foil and bake for 1 hour.

Remove the foil, sprinkle the shredded cheese on top, and return to the oven for an additional 15 minutes or until the cheese is bubbly and golden.

Let it cool for a few minutes before serving.