Preheat oven to 425°. Line 2 large baking sheets with parchment paper and coat with cooking spray. In a shallow bowl, whisk panko, Italian seasoning, an 1/2 cup Parmesan; season with salt and black pepper. In another shallow bowl, whisk eggs with 2 tablespoons water; season with salt and black pepper.
Dip an eggplant slice into egg wash, then dredge in panko mixture. Arrange on prepared baking sheet. Repeat to coat all eggplant slices. Spray tops lightly with cooking spray.
Bake until softened on the inside, and golden and crisp on the outside, 30 to 35 minutes.
In a large baking dish, evenly spread 1 cup marinara. Add an even layer of eggplant slices, then pour 1 1/2 cups marinara on top. Sprinkle with 1 cup mozzarella, half of remaining Parmesan, and basil. Repeat process once more to use up all ingredients.
Bake until bubbly and golden, 15 to 17 minutes more.