Preheat oven to 400°F. Slice zucchini and eggplant ¼-inch thick. Toss with olive oil and salt, spread on a sheet pan, and roast for 20-25 minutes until edges brown and vegetables release moisture. Pat dry with paper towels.
2 medium zucchini, 1 medium eggplant, 2 tablespoons olive oil
Drain ricotta in a mesh strainer for 30 minutes. Transfer to a bowl and mix with egg (if using), grated Parmesan, and minced garlic until smooth.
15 oz ricotta cheese, 0.5 cup Parmesan cheese, 1 egg, 3 cloves garlic
Spread 1 cup marinara sauce in the bottom of a 9x13 inch baking dish. Arrange 4 noodles without overlap, spread half the ricotta mixture over noodles, add half the roasted vegetables, sprinkle one-third of the mozzarella cheese. Repeat layers with sauce, noodles, ricotta, vegetables, and mozzarella. Finish with a final layer of noodles, remaining sauce, and remaining mozzarella.
12 pieces lasagna noodles, 15 oz ricotta cheese, 2 cups mozzarella cheese, 2 medium zucchini, 1 medium eggplant, 3 cups marinara sauce
Cover the dish tightly with foil and bake at 375°F for 30 minutes until sauce bubbles at the edges and noodles soften.
Remove foil and bake an additional 10-15 minutes until cheese browns lightly. Remove from oven and let rest for 15 minutes before slicing with a serrated knife.
