Preheat oven to 350°. Cut eggplant into very thin rounds—on a mandoline, if possible. Lay slices of eggplant on paper towels in an even layer. Season lightly with salt, then let sit for 10 minutes. Wipe any visible moisture off slices with a paper towel and flip. Repeat salting, resting, and drying process once more.
Transfer eggplant slices to a large bowl and toss with oil. Add Parmesan, Italian seasoning, and garlic powder. Season with black pepper and toss until slices are evenly coated.
Arrange eggplant slices in an even layer (make sure none are overlapping!) on a large baking sheet.
Bake until golden and crisp, 16 to 18 minutes. Let cool before serving with marinara.