Preheat oven to 425 degrees F. Line a rimmed baking sheet with parchment paper and coat it with olive oil spray.
Slice the zucchini into 1/8-inch-thick rounds. Arrange the slices on a platter or a tray and sprinkle with kosher salt. Place the salted zucchini in a colander and let stand 30 minutes at room temperature. This should draw water out of the zucchini. After 30 minutes rinse, then dry the zucchini slices using paper towels.
Transfer the dried zucchini slices to a bowl and toss with the olive oil. Place in a single layer on the prepared baking sheet. Bake 15 minutes.
Remove the baking sheet from the oven. Turn each slice to the other side. Lightly spray with olive oil and sprinkle with the garlic powder, salt, pepper and Parmesan.
Return to the oven, rotating the baking sheet, and continue baking until the zucchini slices are browned and crisp, about 15 more minutes. Use a spatula to transfer to individual plates and serve.