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

Heat the olive oil in a large skillet over medium heat. Add the ground beef and cook for 5-7 minutes, breaking it up with a wooden spoon until browned and no pink remains. Drain any excess fat.

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

Spread the cooked beef mixture evenly across the bottom of your prepared baking dish.

Layer the thinly sliced potatoes over the beef, overlapping them slightly. Season each layer generously with salt, pepper, Italian seasoning, and paprika.

Sprinkle both cheeses evenly over the potatoes. Pour the beef broth around the edges of the dish. If using milk, drizzle it over everything now.

Cover the dish tightly with aluminum foil and bake for 30 minutes.

Remove the foil and continue baking for 15-20 minutes until the potatoes are fork-tender and the cheese is golden and bubbly. For extra browning, switch to broil for the last 2-3 minutes, watching closely.

Let the casserole rest for 5 minutes before serving. Garnish with fresh parsley if desired.