Preheat your oven to 350°F (175°C). This ensures your casserole cooks evenly.

In a large skillet over medium heat, cook the ground beef until browned. Add chopped onions and sauté until they become translucent. Season with salt and pepper.

While the beef is cooking, peel and thinly slice the potatoes.

In a large mixing bowl, combine the cooked beef and onion mixture with cream of mushroom soup and milk. Mix well to create a creamy filling.

In a greased 9×13-inch baking dish, arrange half of the sliced potatoes at the bottom. Pour half of the beef mixture over the potatoes. Sprinkle half of the shredded cheddar cheese. Repeat these layers one more time, ending with cheese on top.

If you desire extra crunch, sprinkle breadcrumbs on the top layer of cheese.

Cover the baking dish with aluminum foil and bake in the preheated oven for 30 minutes. Afterward, remove the foil and bake for an additional 20-25 minutes, or until the potatoes are tender and the cheese is bubbly and golden.

Once baked, allow the casserole to cool for a few minutes before serving. Enjoy every comforting bite!