Preheat your oven to 375°F (190°C) and grease a 9x13-inch baking dish with olive oil or butter.

In a skillet over medium heat, brown the ground beef with chopped onion for about 5-7 minutes, then drain excess fat, add garlic and seasoning, and cook for another minute.

Whisk together cream of mushroom soup and milk in a separate bowl until smooth.

Thinly slice your potatoes to about 1/8 inch thick using a mandoline slicer.

Layer sliced potatoes at the bottom of the baking dish, then half the beef mixture, followed by half the cheese. Repeat the layers, finishing with potatoes and remaining cheese.

Cover the casserole with aluminum foil and bake for about 60 minutes, then uncover and bake for an additional 15-20 minutes until golden.

Let the casserole sit for 5 minutes before serving.