Boil and mash the potatoes

• Boil the potatoes in salted water until tender, then drain.
• Mash with the butter, milk and half of the mozzarella until smooth.

Cook the beef filling

• Sauté the onion until soft, then add the garlic.
• Add the ground beef and cook until browned.
• Stir in the tomato sauce, paprika, salt, pepper and sugar, then simmer until slightly thickened.

Assemble the casserole

• Spread the mashed potatoes into a baking dish.
• Add the beef mixture on top.
• Top with the remaining mozzarella.

Bake

• Bake at 200 °C until the cheese is melted and golden.