Preheat the oven to 450°F. Line 2 large, rimmed baking sheets with nonstick foil or high-heat-resistant parchment paper and spray them with olive oil.
Using a sharp knife, slice the eggplants very thinly into ⅛-inch-thick slices.
Arrange the eggplant slices in a single layer on the prepared baking sheets. Spray them with olive oil and sprinkle them with salt, black pepper, and garlic powder.
Bake the chips in the preheated oven for 15 minutes.
Remove the pans from the oven, flip the eggplant slices, spray them with more oil, and bake until browned and crispy, 10-15 more minutes. (See notes). Serve immediately.
Video
Notes
Watch the chips carefully to ensure they don't burn. Not all of them will be ready at the same time, so remove those that are already browned and keep roasting the rest.
I don't recommend making this recipe with regular eggplants. Japanese (or Chinese) eggplants work best not just because they produce smaller, chip-like rounds but also because of their firmer texture and lower water content.
These chips are best enjoyed fresh, but you can keep the leftovers in an airtight container in the fridge for up to four days. Reheat them uncovered in a 350°F oven or enjoy them cold, antipasti-style.