Grease an 800ml pudding basin and place a small circle of baking parchment in the bottom.
Cream the butter and sugar until light and fluffy. Whisk in the eggs, one at a time, with 1 tablespoon of the flour. Fold through the rest of the flour, as well as the cocoa, ginger, half of the clementine zest, the clementine juice and 1 tablespoon of the chocolate sauce.
Pour into the pudding basin, then push the whole zested clementine into the mixture, so it’s enclosed.
Grease a square of baking parchment and put it over the top of the bowl, then lay a square of foil over the paper and tie them tightly around the rim with string.
Put an upturned side plate in a large pan, then sit the pudding basin on top. Pour in enough boiling water to come 2 inches up the sides. Simmer, covered, for 1 hour 45 mins. Remove and allow to rest for 5 minutes before turning out.
Heat the remaining sauce in a pan and pour over the pudding. Decorate with the clementine segments and remaining zest.