01 - Preheat oven to 400°F (200°F). Line two baking sheets with parchment paper.
02 - Arrange eggplant slices on the prepared sheets. Brush both sides lightly with olive oil and sprinkle with kosher salt and black pepper.
03 - Bake eggplant slices for 15 to 20 minutes, flipping halfway, until softened and pliable but not overly browned. Remove from oven and allow to cool slightly. Lower oven temperature to 375°F (190°C).
04 - Heat a skillet over medium heat. Add a little olive oil and sauté minced garlic for 30 seconds. Add chopped spinach; cook until wilted. Transfer mixture to a bowl and cool.
05 - In a large bowl, combine ricotta, Parmesan, half the mozzarella, cooked spinach, beaten egg, ground nutmeg, Italian herbs, black pepper, kosher salt, and sliced basil. Mix thoroughly.
06 - Spread 1 cup marinara sauce evenly over the bottom of a 9x13-inch baking dish.
07 - Place 2 to 3 tablespoons of ricotta mixture at the end of each eggplant slice. Roll tightly and arrange seam-side down in the baking dish.
08 - Cover the rolls with remaining marinara sauce. Sprinkle with remaining mozzarella cheese. Bake uncovered at 375°F (190°C) for 25 minutes, until bubbling and cheese is golden.
09 - Allow to rest for 5 to 10 minutes after baking. Garnish with fresh basil before serving.