Preheat your oven to 375°. Cut the ends off the zucchini and slice lengthwise into thin slices.
Using a large cookie sheet (you may need 2), cover with parchment paper then place a wire cooling rack on top of parchment paper. Place sliced zuchinni in single layer on the wire rack on cookie sheet. Sprinkle with seas salt. Bake for 10-12 min. Set aside until ready to use. This step can be skipped but the salting and cooking helps to draw out the extra moisture from your zucchini which can make your lasagna a little watery. While zucchini is cooking, make the sausage mixture. Heat a large skillet over medium high heat. Add oil, then add sausage and saute until browned, stirring as needed. about 3-5 minutes. Lower the heat to medium and add in the onions and saute until translucent. Add the garlic, stir, then sprinkle with salt, pepper, Italian seasoning, and crushed red pepper, if desired.
Cook and stir until softened, then add the spinach or kale and stir until wilted. Add in 1 cup of marinara and stir to heat through, then remove from heat.
Spread ½ cup of remaining marinara onto the bottom of the 9×13" casserole dish.
Add zucchini slices on top of the pasta sauce side by side. Top the zucchini with ½ of the sausage mixture and evenly spread ⅓ of the cheese sauce on top. Sprinkle ⅓ of the chopped fresh herbs on top.
Repeat these layers, leaving enough zucchini for a final top layer.
Top the lasagna with the last layer of zucchini, remaining cheese sauce, and remaining parsley and basil. Bake in the preheated oven (middle rack) for 20-25 minutes, until hot and bubbly. Garnish with basil before serving. Enjoy!
