The pumpkin or squash needs to be a firm-fleshed variety, rather than one of the big, woolly types best suited to Hallowe’en lanterns. Michael suggests Crown Prince winter squash, “because of the nutty flavour and robust flesh”. Adding some pumpkin seeds gives extra texture, for the perfect loaf.
Mix the starter, both flours and the water for the pre-ferment together thoroughly, cover and leave at room temperature for 16–18 hours (typically overnight).
Heat the oven to 180°C/160°C fan/350°F/gas 4. Cut the pumpkin in half, scoop out