1) Preheat the oven to 230C/Gas 8. Coat a baking sheet with cooking spray.
2) Slice the courgettes into 0.5cm thick rounds. In a medium bowl, toss the courgettes with the oil. In a small bowl, combine the Parmesan, bread crumbs, salt, and a few turns of pepper. Dip each round into the Parmesan mixture, coating it evenly on both sides, pressing the coating on to stick, and place in a single layer on the prepared baking sheet.
3) Bake the courgette rounds until browned and crisp, 25 to 30 mins. Remove with spatula. Serve immediately.