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

In a large skillet, add ground beef and diced onion. Cook until beef is browned and onion is translucent, about 6-8 minutes. Drain excess fat, then stir in minced garlic, salt, pepper, and paprika. Cook for an additional 1-2 minutes.

Blend in cream of mushroom soup and milk, stirring until smooth.

Wash and slice the potatoes into 1/8-inch thick rounds. Set aside for layering.

Layer half of the sliced potatoes in the bottom of the prepared baking dish. Spread half of the beef mixture over the potatoes, followed by half of the shredded cheddar cheese. Repeat the layering process.

Cover the baking dish tightly with aluminum foil and bake for 60 minutes.

After 60 minutes, remove the foil and bake for an additional 15-20 minutes until the cheese is golden brown.

Let the casserole rest for about 5 minutes before serving.