Pre-heat the oven to 180ºC
Peel the squash or pumpkin and cut into large chunks. Place on a large roasting tray and chuck on the squash chunks. Pop in the oven for 25 minutes or so until soft but not crispy brown.
Once the squash has been in the oven for 10 minutes, roughly chop the onion, ginger and garlic, and pop in a small food processor. Blitz with a little water until you have a thick paste.
Heat a couple of tablespoons of water in the base of a large saucepan. Add the onion, ginger and garlic mix and sauté gently for 10 minutes until soft. Add more water if needed to stop it sticking to the base of the pan.
By now the squash should be soft and slightly caramelised, so remove from the oven and carefully tip it into the saucepan. Cover with vegetable stock but take care as you may not need all 600mls - the squash will release more fluid whilst simmering, so you don't want it to be too watery.
Leave to simmer gently for another 10 minutes or so then turn off the heat. Puree with a stick blender, adding more of the vegetable stock if needed to get the thickness you like.
Season with salt and pepper to taste (it can take a good pinch of salt if you can have added salt) and serve piping hot with a garnish or chopped parsley or coriander and a swirl of flaxseed oil if you desire.
