Preheat your oven to 375°F (190°C). Lightly grease the baking dish with butter or cooking spray. This prevents sticking and helps the casserole bake evenly from top to bottom.

Heat olive oil in a large skillet over medium heat. Add diced onion and cook until soft. Stir in garlic, then add ground beef. Cook until browned and fully cooked.

Add salt, black pepper, paprika, and Italian seasoning to the cooked beef. Mix everything well so every bite has delicious flavor. Pour in beef broth and simmer for three minutes.

Peel the potatoes and slice them very thin. Thin slices cook faster and become soft during baking. Pat the slices dry with paper towels before layering them.

In a bowl, mix heavy cream with thyme. Stir until smooth. This creamy mixture keeps the potatoes soft and adds rich flavor throughout the casserole.

Arrange one layer of potatoes in the baking dish. Add half of the beef mixture. Sprinkle cheddar cheese. Repeat the layers, then pour the cream mixture evenly over everything.

Top the casserole with mozzarella and the remaining cheddar cheese. Cover the dish with aluminum foil to keep moisture inside while the potatoes become tender.

Bake for 40 minutes covered. Remove the foil and bake another 15 minutes until the cheese becomes golden, bubbly, and lightly browned. Sprinkle fresh parsley before serving.