Preheat oven to 375°F (190°C). Grease a baking dish.
In a skillet, cook ground beef and diced onion over medium heat until browned. Drain excess grease.
In a bowl, mix cream of mushroom soup and milk until combined.
Layer half of the sliced potatoes in the baking dish, season with salt, pepper, garlic powder, and paprika.
Add half of the cooked beef mixture and pour half of the soup mixture over it.
Repeat the layers and top with shredded cheese.
Cover with foil and bake for 45 minutes. Remove foil and bake for another 15 minutes until golden and bubbly.
Let sit for 5 minutes before serving.