Preheat the oven to 350°F and coat a shallow baking pan with cooking spray.
Quarter the zucchini lengthwise, then cut crosswise into 1-1/2-inch pieces. Place the zucchini in a bowl, drizzle with olive oil, season with salt and pepper and toss to combine.
Arrange the zucchini, cut side up, in a single layer on the prepared baking pan. Roast until tender, 20 to 25 minutes, then remove from the oven, sprinkle with the grated parmesan and continue roasting until golden, 5 to 7 minutes longer.