Make the ragù

• Sweat the onion, carrot, celery and garlic in the olive oil until soft.
• Add the ground beef and brown it well, breaking it up.
• Pour in the red wine and let it evaporate.

Simmer the sauce

• Add the tomato passata, tomato paste, oregano, salt and pepper.
• Simmer gently, stirring occasionally, until thick and rich.

Cook the conchiglioni

• Boil the shells in salted water until just shy of al dente.
• Drain and rinse briefly under cold water so they are easy to handle.

Fill the shells

• Spoon a little ragù into the baking dish.
• Fill each shell with ragù and arrange them in the dish.

Top and bake

• Pour the béchamel over the shells and scatter with mozzarella and parmesan.
• Bake until golden and bubbling.

Rest and serve

• Let the bake rest for a few minutes before serving.