Preheat the oven to 425°F. Line a rimmed baking sheet with high-heat-resistant parchment paper and coat it with olive oil spray.
Slice the zucchini into ⅛-inch-thick rounds.
Arrange the zucchini rounds on paper towels. Sprinkle them with salt and let them stand at room temperature for 30 minutes to draw out excess water. After 30 minutes, blot them thoroughly dry with paper towels to remove the surface water and some of the salt.
Arrange the zucchini slices in a single layer on the prepared baking sheet. Spray them with olive oil. Bake them for 15 minutes.
Remove the baking sheet from the oven. Sprinkle the zucchini slices with black pepper, garlic powder, and grated Parmesan.
Return the pan to the oven and continue baking until the zucchini slices are browned and crisp, 15-20 more minutes. Check them every 5 minutes, remove the ones that are ready to a plate, and keep baking the ones that are still soft.
Serve immediately.
