Preheat the oven to 450 degrees F. Line 2 baking sheets with parchment paper and set aside.
Trim the ends of the zucchini then, using a mandoline, slice into ¼ inch thick “lasagna noodles”. Divide the strips between the prepared baking sheets, drizzle them with olive oil, sprinkle with 1 teaspoon salt, and roast for 10 minutes. Remove the pans from the oven and set aside to cool. Reduce oven temperature to 375 degrees F after baking zucchini.
Meanwhile, in a large skillet, cook the ground turkey with the mushrooms and onion over medium-high heat for 6-8 minutes until fully cooked. Stir in Italian seasoning, ½ teaspoon salt, ¼ teaspoon black pepper, and pasta sauce, then bring it to a boil. Reduce heat to low and simmer, uncovered, for 5 minutes.
In a medium mixing bowl, combine ricotta cheese, egg, remaining salt and pepper, 1 cup of mozzarella, and ¼ cup Parmesan; mix well.
Spread ½ cup of meat sauce on the bottom of a 13x9-inch baking dish coated with cooking spray. Place a single layer of zucchini noodles on top, then carefully spread on half of the cheese mixture, followed by ⅓ of the meat sauce. Repeat the layers - noodles, remaining cheese, ⅓ of the sauce. Place a final layer of noodles on top, the remaining sauce, then sprinkle with the mozzarella and Parmesan.
Bake, uncovered, for 40 minutes. Allow the lasagna to sit for 10-15 minutes before serving.