Preheat your oven to 180C and peel your butternut squash using a knife. Cut it into cubes about 1 inch square and toss with half of the coconut oil, then place in the oven for about 20 minutes.
After 20 minutes, add the garlic and rosemary and return to the oven for another 20-25 minutes, or until soft.
Meanwhile, heat the other tbsp of coconut oil in a large pot and add the onion. Place the lid on the pot and leave the onion to sweat and soften, then add the butternut squash cubes and the cloves of garlic. Discard the rosemary sticks, but put in the rosemary leaves for more flavour! Add 2 cups of water and simmer for 10-15 minutes.
Allow to cool slightly, then using a immersion blender, blend smooth, adding the extra cup of water for a smoother soup.