For the cake, place the whole orange in a small saucepan, cover with boiling water and boil for 30 minutes, or until soft. Leave to cool. When the orange is cold, cut in half and remove any pips.

Preheat the oven to 160C/325F/Gas 3 and grease and line a 24cm/9½in loaf tin or a 20cm/8in cake tin. Weigh the orange pulp and keep 450g/1lb (discard the rest). Place back in food processor with ...