Prepare the leeks and garlic as above. Remove the cauliflower stems from the florets. Chop the stems and put to one side. Chop the florets and reserved leaves.
Heat 2 tablespoons of water in the base of a large saucepan. Add the leeks, cauliflower stems and bay leaf. Saute on a medium heat for 5 minutes until the leek is softened. Add extra water if needed.
Add the raw garlic if using and continue to saute for a couple of minutes.
Tip the chopped cauliflower florets and leaves into the pan along with the dried thyme. If you are using chopped chestnuts, add these to the pan now. Cover with vegetable stock and bring to the boil.
Turn down the heat and simmer for 10 minutes. Add the chestnut puree to the pan and continue to simmer for another 10 minutes or until the cauliflower and chestnuts are soft and a little mushy.
Turn off the heat and add the dairy free milk to the pan. Blend to smooth with a stick blender then put the pan back on the heat and bring to a gentle simmer.
Simmer for another 5 minutes to make sure everything is piping hot. Season with salt and pepper.
Serve the soup garnished with a sprinkle of chopped chestnuts and thyme and a glug of flaxseed or olive oil.
