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

In a large skillet, heat the olive oil over medium heat. Add the ground beef and cook, breaking it apart with a spoon, until browned and cooked through (about 5-7 minutes). Drain any excess fat if needed.

Add the chopped onion and minced garlic to the skillet with the beef. Cook for another 3-4 minutes until the onion becomes soft and translucent.

Layer the thinly sliced potatoes on top of the ground beef in the prepared baking dish. Spread the cooked ground beef mixture evenly in the bottom of the dish, then arrange the potatoes on top, seasoning them with salt, pepper, Italian seasoning, and paprika.

Sprinkle the shredded cheddar and grated Parmesan cheese over the beef. Pour the beef broth (or water) around the edges of the casserole to keep the potatoes moist while baking. Optionally, drizzle with milk for extra creaminess.

Cover the casserole with aluminum foil and bake for 30 minutes. After 30 minutes, remove the foil and bake for an additional 15-20 minutes, or until the potatoes are tender and the cheese is bubbly and golden.

Garnish with fresh parsley if desired and serve hot!