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