Place zucchini slices in a colander, sprinkle with salt, and let drain for 15 minutes. Pat dry with paper towels.
Preheat oven to 375°F and spray a 9x13-inch baking dish with cooking spray.
In a large bowl, mix ricotta cheese, eggs, Italian seasoning, and garlic until well combined.
Spread 1 cup of marinara sauce on the bottom of the prepared baking dish.
Layer one-third of the zucchini slices over the sauce, followed by one-third of the ricotta mixture, 1 cup mozzarella, and 1 cup marinara.
Repeat layers two more times, ending with remaining mozzarella and Parmesan cheese on top.
Cover with foil and bake for 30 minutes, then uncover and bake for an additional 15 minutes until golden and bubbly.
Let stand for 10 minutes before serving, then garnish with fresh basil.