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

In a large skillet, brown ground beef over medium heat for 5–7 minutes. Drain excess fat, then add diced onion and minced garlic. Season with salt, pepper, and paprika, and sauté for 2–3 minutes until translucent.

Stir in cream of mushroom soup and ½ cup of milk, blending until smooth. Allow to simmer for a minute.

Slice potatoes thinly, about 1/8 inch thick. Layer in the baking dish: first, add potatoes, then half the beef mixture, and half the cheese. Repeat layers.

Add the last layer of potatoes, remaining beef mixture, and finish with the remaining cheese on top.

Cover the dish with foil and bake for 60 minutes until potatoes are fork-tender.

Remove the foil and bake for an additional 15–20 minutes until cheese is bubbly and golden brown.

Let the casserole rest for 5 minutes before serving.