Position racks in middle and lower thirds of oven; preheat to 450°F. Coat 2 large rimmed baking sheets with cooking spray. Arrange eggplant slices in a single layer on the prepared baking sheets. Generously brush both sides of the eggplant with 3 tablespoons oil. Roast until tender and golden brown, about 20 minutes, flipping the slices and rotating the pans between the top and bottom racks halfway through.

Combine marinara, ⅓ cup basil, 1½ teaspoons oregano and the grated garlic in a medium bowl. Spoon about ⅓ cup of the sauce over the bottom of a large skillet. Arrange half of the roasted eggplant slices in an even layer over the sauce. Top with 1⅓ cups sauce; scatter half of the torn mozzarella over the sauce. Sprinkle with 1 tablespoon Parmesan. Arrange the remaining eggplant slices in an even layer over the Parmesan. Top with the remaining 1⅓ cups sauce, the remaining mozzarella and 2 tablespoons Parmesan. Bake until the cheese has started to melt and the sauce bubbles around the pan edges, about 10 minutes.

Stir ¼ cup panko and the remaining 1 tablespoon oil together in a small bowl; sprinkle over the melted cheese. Return the skillet to the oven; increase oven temperature to broil. Broil until the panko is golden brown, about 4 minutes. Sprinkle with the remaining 1 tablespoon Parmesan. Let stand for about 10 minutes before serving. Garnish with basil leaves, if desired.