Preheat your oven to 350°F (175°C) and lightly grease a 9×13-inch baking dish with non-stick spray or oil.

In a large skillet, heat the olive oil or butter over medium heat. Add the diced onion and cook for 2–3 minutes until slightly soft.

Add the ground beef to the skillet, breaking it apart with a spoon. Cook until browned and fully cooked, about 6–8 minutes. Season with salt, pepper, garlic powder, and onion powder. Drain excess grease if needed.

While the beef cooks, thinly slice the potatoes. A mandolin helps here, but a sharp knife works fine. Aim for slices about 1/8 inch thick.

In a bowl, mix the cream of mushroom soup and milk until smooth. Set aside.

Start layering in the baking dish:

• First, a layer of sliced potatoes

• Then, a layer of the cooked ground beef mixture

• Pour a bit of the soup mixture on top

• Sprinkle with a handful of shredded cheese

• Repeat layers until all ingredients are used, finishing with cheese on top

Cover the dish with aluminum foil and bake for 45 minutes.

Uncover and bake an additional 15–20 minutes until the cheese is golden and bubbly and the potatoes are fork-tender.

Let it rest for 10 minutes before serving to allow it to set properly.