1. Cook the manicotti shells in a large pot of lightly salted water according to the package instructions. Drain, rinse under cold running water, and drain again.
2. Meanwhile, drain the spinach well, pressing out any excess liquid. Mix the ricotta, ½ cup of the Parmesan, and the eggs in a bowl. Add the spinach and mix. Season with the nutmeg, salt, and pepper. Spoon the filling into the manicotti tubes. Arrange them in a lightly oiled 15 × 10in (38 × 25cm) baking dish.
3. For the sauce, heat the oil in a saucepan over medium-low heat. Add the onion and cook for 5 minutes, until softened. Add the celery and garlic and cook for another 2 minutes. Stir in the tomatoes and stock and simmer for 15 minutes, or until the sauce is slightly reduced. Stir in the basil.
4. Preheat the oven to 375°F (190°C). Pour the white sauce over the manicotti, then spoon the tomato sauce on top. Sprinkle with the remaining ¼ cup of Parmesan. Bake for 30–35 minutes, or until the top is golden and bubbling.
Nutritional information is based on 8 servings, 1/8 teaspoon of added salt per serving, but does not include bechamel sauce. For nutritional information on bechamel sauce, please follow the link above.