Preheat the oven to 425F.
Arrange the mushroom slices on a baking sheet and spray with cooking spray. Season with a pinch of salt and a few grinds of black pepper. Flip and repeat.
On a separate baking sheet, arrange the zucchini slices. Spray with the cooking spray, season with a pinch of salt, and a few grinds of black pepper. Flip and repeat.
Put the two trays in the oven and roast the veggies for 6-7 minutes. Take them out, carefully flip, and roast until tender and brown. This should be another 5-6 minutes. Set aside to cool slightly. Reduce the heat in your oven to 375F.
Create your ricotta mixture. Mix the ricotta, the 2 eggs, basil, parsley, nutmeg, and a healthy pinch of kosher salt until evenly combined. Set aside.
Assemble your lasagna. Spread 1 ½ cups of the marinara in the bottom of the baking dish. Arrange the noodles so the edges touch the marinara. You may need to break one into pieces to fill in the very end of the pan.
Spread 1 1/2 cups of the ricotta over the noodles gently. Arrange half of the mushrooms over that evenly followed by half of the zucchini slices. Sprinkle half of the spinach over this followed by ½ cup of the shredded mozzarella and another 1 ½ cups of marinara.
Add another layer of noodles followed by ½ cup of the shredded mozzarella and 1 ½ cups of marinara.
Add another layer of noodles. On top of this spread 1 1/2 cups of the ricotta mix evenly followed by the remainder of the mushrooms, zucchini, spinach, and another ½ cup of the mozzarella.
Add another layer of noodles. Top with the remaining ricotta and the last 1 ½ cups of marinara.
Cover the dish with aluminum foil and bake for 45 minutes at 375F.
Remove the pan, remove the foil, and top with a good layer of mozzarella followed by a healthy dose of fresh parmesan. Return to the oven for another 10-15 minutes or until the cheese is bubbling and the corners are brown.
Allow to cool for 10-15 minutes before cutting and serving. Enjoy!