Preheat the oven to 375F and spray a baking sheet with cooking spray.

Build the lasagna. Spread a thin layer of marinara in the bottom of the baking dish, then make a layer of zucchini, overlapping the pieces to completely cover the bottom of the baking dish. Sprinkle the zucchini lightly with salt. Spread a bit more marinara over the zucchini, then spread on a handful of cheese and a layer of spinach leaves.

Repeat the layers, starting this time with eggplant: eggplant, salt, sauce, cheese, spinach. Repeat, alternating the veggies (or making some layers with eggplant and zucchini to use everything up), until you have as many layers as you can fit in the baking dish. Top the lasagna with a final layer of marinara then any remaining cheese.

Bake the lasagna for one hour and 15 minutes uncovered, then remove it from the oven to test it. A fork should go easily through the layers of the vegetables and the cheese should be starting to brown.

Bake the lasagna for up to 30 minutes more to cook the veggies through and allow as much liquid as possible to evaporate. If the cheese becomes very brown before the lasagna is done, place a piece of foil very lightly over the dish to allow steam to still escape on all sides.

When the lasagna is done, let it rest uncovered for 15-30 minutes, then cut into pieces and serve. If there is a lot of liquid in the bottom of the dish, tilt the dish and discard the veggie juices with a spoon.

Serve the lasagna with extra marinara and fresh herbs for sprinkling.

Enjoy!