01 - Preheat oven to 400°F. Line two baking sheets with parchment paper.
02 - Arrange eggplant planks in a single layer on the prepared sheets. Brush both sides with olive oil and season with kosher salt and black pepper.
03 - Bake eggplant for 15 to 20 minutes, flipping halfway through, until softened and pliable but not browned. Allow slices to cool slightly. Reduce oven temperature to 375°F.
04 - Heat a skillet over medium heat with a small amount of olive oil. Sauté minced garlic for 30 seconds, then add spinach and cook until wilted. Transfer to a bowl to cool.
05 - In a large mixing bowl, combine ricotta, Parmesan, half the mozzarella cheese, the cooled spinach, beaten egg, ground nutmeg, dried Italian herbs, black pepper, kosher salt, and sliced basil. Mix thoroughly.
06 - Spread 1 cup of marinara sauce evenly over the bottom of a 9x13-inch baking dish. Place 2 to 3 tablespoons of cheese filling at one end of each eggplant slice, roll tightly, and set seam-side down in the prepared dish.
07 - Pour remaining marinara sauce over the arranged rollatini. Evenly top with the rest of the mozzarella cheese.
08 - Bake uncovered at 375°F for 25 minutes, or until bubbling and golden. Allow to rest for 5 to 10 minutes before serving. Garnish with additional fresh basil.