Prepare the spinach mixture

• Dice the onion, grate the garlic and chop the spinach.
• Heat a little olive oil in a pan over medium heat.

Sauté the vegetables

• Sauté the onion for a few minutes, then add the garlic and cook for about 1 minute.
• Add the chopped spinach, season with salt and black pepper and cook until wilted.
• Remove from the heat and let cool slightly.

Make the filling

• In a bowl, combine the cooked spinach mixture with the ricotta, half of the mozzarella, half of the parmesan and some chopped basil.
• Mix until smooth and uniform, then taste and adjust the seasoning.

Prepare the tomato sauce

• In a clean pan, heat a little olive oil over medium heat and cook the remaining grated garlic for about 1 minute.
• Pour in the tomato polpa, add fresh basil and a pinch of dried oregano.
• Let it simmer briefly to combine the flavors.

Cook the pasta

• Cook the conchiglioni in salted boiling water until al dente, 2 minutes less than the package instructions.
• Drain and let cool slightly.

Fill and assemble

• Fill each shell with the ricotta-spinach mixture using a spoon or a piping bag.
• Spread some tomato sauce on the bottom of a baking dish and arrange the filled shells on top.
• Pour the remaining sauce over them and sprinkle with the rest of the mozzarella and parmesan.

Bake

• Bake at 180 °C until the cheese melts and slightly browns.
• Garnish with fresh basil before serving.