Vegetarian Lasagna with Roasted Vegetables

Steps

1. Preheat the oven to 425°F (220°C). Cut the zucchini and eggplant into 3/4 inch (2 cm) dice, the red peppers into 3/4 inch (2 cm) strips, and the red onions into thin wedges. Toss them on two sheet pans with 5 tablespoons of the olive oil, the oregano, 1 teaspoon of the salt, and the black pepper, and spread them out in a single layer without crowding.
2. Roast for 30 to 35 minutes, swapping the pans and turning the vegetables halfway through, until they have shrunk, their edges are well browned, and the eggplant is meltingly soft. Take them out and lower the oven to 375°F (190°C).
3. While the vegetables roast, make the sauce: in a saucepan, heat 1 tablespoon of the olive oil over medium heat, add the sliced garlic and red pepper flakes for 1 minute, then the tomato paste for 1 minute, stirring, until it darkens. Pour in the crushed tomatoes, add the basil stems and 1/2 teaspoon of the salt, and simmer for 20 minutes. Remove the stems: the sauce should stay loose enough to pour.
4. Wilt the baby spinach in a large dry skillet over high heat for 2 minutes, tip it into a colander and let it cool slightly, then squeeze it between your hands until no more water comes out. Chop it roughly.
5. In a bowl, mix the ricotta, spinach, egg, 40 g (about 1/2 cup) of the grated hard cheese, the nutmeg, and the rest of the salt. Shred the mozzarella.
6. Lay the lasagna noodles in a large dish filled with the 2 l (about 2 quarts) of very hot tap water and let them soften for 10 minutes, separating them now and then so they do not stick. Drain them on a kitchen towel.
7. Build the lasagna in a 9 x 13 inch (23 x 33 cm) baking dish: spread one fifth of the sauce over the bottom, then a layer of noodles, one third of the roasted vegetables, one third of the ricotta mixture in small dollops spread with the back of a spoon, one fifth of the sauce, and 50 g (1/2 cup) of mozzarella. Repeat these layers twice more.
8. Finish with a final layer of noodles, then the rest of the sauce, making sure the edges of the pasta are covered so they do not harden, the remaining 100 g (1 cup) of mozzarella, and the remaining 40 g (1/2 cup) of hard cheese.
9. Cover with foil, tented so it does not touch the cheese, and bake for 30 minutes at 375°F (190°C). Remove the foil and bake for 20 more minutes, until the top is golden and bubbling and the tip of a knife slides through the noodles with no resistance.
10. Let rest for 15 minutes before cutting: the ricotta and the pasta starch firm up as they cool slightly, so the slices come out neatly instead of collapsing. Scatter with fresh basil leaves and serve.