Preheat your oven to 350°F (175°C).

In a large skillet, heat a tablespoon of olive oil over medium heat. Add the chopped onions and sauté until they become translucent, about 5 minutes.

Add the ground beef, breaking it apart with a spatula as it cooks until browned and no longer pink, about 7-10 minutes. Drain any excess fat.

In a mixing bowl, combine the cream of mushroom soup, cream of celery soup, milk, salt, and black pepper. Whisk until well blended.

Grease your baking dish with olive oil. Layer half of the sliced potatoes evenly across the bottom.

Spread half of the browned ground beef mixture over the first layer of potatoes.

Pour half of the creamy mixture over the beef, covering the layer thoroughly.

Repeat by layering the remaining sliced potatoes on top, followed by the rest of the ground beef and the remaining creamy mixture.

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

After 1 hour, remove the foil and sprinkle the top with shredded cheddar cheese. Return to the oven uncovered for an additional 15-20 minutes, or until cheese is melted and golden.

Remove from the oven and let cool for a few minutes before serving.