Preheat the oven to 200 C, Fan 180, Gas 6. Cut the squash in half, remove the seeds and chop the flesh into large chunks.
Put the squash and the olive oil into an ovenproof dish and add the rosemary and garlic. Mix well and roast for about 30 minutes until soft then remove from the oven and set aside.
Whisk together the ingredients for the vinaigrette.
Cut the beetroot into large chunks and mix with the squash in a serving bowl. Saute the pancetta in a dash of oil and add to the beetroot and squash.
Add the spinach, parsley and vinaigrette and mix well- the spinach will wilt in the heat of the squash.