Cooking spray
1 (15-ounce) tub ricotta
1 (10-ounce) package chopped frozen spinach, thawed and squeezed to drain out excess liquid
1 large egg, lightly beaten
1/2 cup grated Parmesan cheese, divided
1 teaspoon dried oregano
1/2 teaspoon salt
1/2 teaspoon pepper
1 (32-ounce) jar pasta sauce
1 pound uncooked lasagna noodles
2 pounds zucchini, sliced into long strips
2 cups shredded mozzarella cheese
Preheat the oven to 350 degrees F and spray a 13-by-9-inch baking dish with cooking spray.
In a medium bowl, stir together the ricotta, spinach, egg, 1/4 cup of the Parmesan, oregano, salt and pepper.
Spread about 1/2 cup of sauce over the bottom of the prepared baking dish. Arrange one-third of the uncooked noodles in a layer covering the bottom of the pan.
Top the noodles with a layer of half of the zucchini slices. Dollop half of the ricotta mixture over the zucchini and then sprinkle one-third of the mozzarella cheese over that.
Repeat with a second layer of noodles (half of the remaining noodles), the remaining zucchini, the remaining ricotta mixture and half of the remaining mozzarella cheese.
End with a layer of noodles, and pour the remaining sauce over the whole thing, making sure to get sauce down into the sides of the pan.
Sprinkle the remaining mozzarella and Parmesan cheese over the top.
Cover with aluminum foil and bake for 45 minutes. Remove the foil and continue to bake until the cheese on top is melted, browned and bubbly, about 15 minutes more.
Remove from the oven and let rest for 15 minutes before serving.
Serve hot.