Salt zucchini in a colander; drain 15 minutes and pat dry with paper towels.
Preheat oven to 375°F; spray a 9x13-inch dish with cooking spray.
Mix ricotta, eggs, Italian seasoning, and garlic well in a large bowl.
Spread 1 cup marinara in prepared dish's bottom.
Layer one-third of zucchini, one-third of ricotta mixture, 1 cup mozzarella, and 1 cup marinara.
Repeat two more times; top with remaining mozzarella and Parmesan.
Cover with foil; bake 30 minutes. Uncover; bake another 15 minutes, until golden and bubbly.
Stand 10 minutes; garnish with basil and serve.