1️⃣ Preheat the oven to 350°F (175°C) and grease a 13×9-inch baking dish.
2️⃣ Sauté the crumbled ground beef and diced onion in a skillet until the beef is cooked through and the onion softens.
3️⃣ Slice the potatoes into ¼-inch rounds and layer them in the prepared baking dish.
4️⃣ Season the potatoes with salt and pepper, then layer with a third of the beef mixture and a third of the shredded cheddar cheese. Repeat the layers twice, ending with a layer of cheese on top.
5️⃣ Mix together the evaporated milk, whole milk, and cheese soup, and pour it over the casserole.
6️⃣ Cover with foil and bake for 1 hour.
7️⃣ Remove the foil and bake for an additional 15 minutes to brown the cheese.
8️⃣ Allow to cool for 5 minutes before serving. Enjoy!