Preheat the oven to 200C. Chop the top off the garlic bulb so the tops of the cloves are exposed. Wrap lightly in foil and roast for an hour. Then leave to cool before removing the skins.
Add all the ingredients to a high-powered blender and mix until smooth. If it’s too thick, add more water.
Serve with extra olive oil drizzled on top and a sprig of rosemary. Enjoy!