Heat oven to 200C/180C fan/ gas 6. Place the butternut squash cut-side up on a baking sheet.
Cover with foil and roast in the oven for 45 mins, put the garlic on the tray and roast for another 15 mins or until you can easily slip a knife through the flesh of the squash.
Take the garlic out if necessary.
Allow to cool a little, then scoop the flesh out of the squash with a spoon, discarding the seeds and skin. Squeeze the garlic out of the skin, discarding any tough bits and purée the garlic pulp together with the squash in a food processor.
You can add a knob of butter, or a splash of water or milk to loosen the purée.