Prepare the sauce by browning the pressed garlic clove in a saucepan with a good tablespoon of olive oil. As soon as it begins to color add the tomato sauce, salt, pepper and cook over medium heat for 10 minutes. Pour the sauce into a baking dish.
Prepare the stuffing. Rinse the spinach well, cut it into strips and sauté it in a frying pan (without fat) for 5 minutes, until the leaves brown. Remove from the heat and stir in the ricotta. Season with salt and pepper, stir in the egg then add the parmesan and a pinch of nutmeg. Mix well. You should get a consistent but still soft dough.
Preheat your oven to 180°C/356°F.
In a large saucepan, bring water to a boil then season with salt. Immerse the conchiglioni pasta in it and stir gently from time to time during cooking. Cook 5 minutes less than the time indicated on the package (in my case, 15 minutes so 10). Drain them with a slotted spoon and place them next to each other on the sauce in the oven dish.
Fill each pastry with stuffing and sprinkle with parmesan. Add a few pine nuts on top for decoration.
Bake for about 30 minutes until everything is nicely browned.