Trim ends and slice each zucchini into thin lengthwise ribbons.

If zucchini is very watery, lightly salt and let sit for 5–10 minutes, then pat dry.

Heat a skillet over medium. Spray with oil. Add zucchini in a single layer if possible, season with salt and pepper, and cook for 8–10 minutes until softened.

Remove zucchini from the skillet and set aside.

In the same skillet, spray again and add chopped spinach. Cook until just wilted. Transfer spinach to a plate lined with a towel and squeeze out excess moisture.

In a medium bowl, combine ricotta, grated Parmesan, beaten egg, minced garlic, chopped basil, chopped parsley, and crushed red pepper. Stir in squeezed spinach and season with salt and pepper.

Coat a 13 x 9-inch casserole dish with cooking spray and spread 1/2 cup marinara on the bottom.

Lay down a layer of cooked gluten-free noodles, then add a layer of zucchini ribbons, half the ricotta mixture, and some mozzarella.

Repeat layers with remaining noodles, zucchini, ricotta, and mozzarella.

Top with a final layer of noodles, the remaining marinara, and the rest of the mozzarella.

Cover loosely with foil and bake at 350°F for 30 minutes. Remove foil for the last 5–10 minutes for browning.

Let the lasagna rest for 15 minutes before cutting to help the layers set.