Wash the squash outside well, dry it, then cut it in quarters. With a large spoon scoop out the seeds.
Cut the quarters into thick slices.
Arrange the slices in one layer on a baking try, drizzle with olive oil and sprinkle with sea salt and cayenne pepper. Toss (with hands) to coat each slice with oil, salt and cayenne pepper. Add torn rosemary sprigs.
Roast the slices in the oven at 200°C for 20 to 30 minutes, flipping them midway during baking, until they’re cooked through and golden.