Slice into 1 inch think slices and remove the seeds.
Peel & quarter the onions.
Pour a little oil into a large baking dish or tray and add all the veggies and the rosemary, tossing well to coat lightly in oil.
Roast for 1 hour or until the vegetables have started to turn golden and feel soft when pierced with a knife.
Remove from the oven and let cool.
Peel & discard the skin from the squash and the rosemary sprigs, adding everything else to a large pan. Don't worry if there are pieces of rosemary leaves left in.
Add the stock or water, and blitz with a stick blender.