Preheat oven to 190°C.
Cut the squash in half, don't peel it, just remove the seeds, then cut it into crescent-shaped wedges.
Deseed the chilli and chop it finely. Don't peel the garlic cloves, just flatten them with a spatula or flat knife.
Cut the rosemary sprigs into 5 cm long pieces.
Place the squash wedges on a baking tray, then scatter the garlic, rosemary & chilli around them. Season with salt and pepper, then sprinkle with the olive oil. Toss everything well.
Bake for about 40-45 minutes until tender.
Just before serving: Dry-fry the nuts until lightly toasted and scatter these on top of the roasted squash.