Method

Preheat the oven to 180C, fan oven 160C, Gas Mark 4.

Cream 175g/6oz unsalted butter and 175g/6oz caster sugar together until pale, light and fluffy, then gradually beat in 2 eggs.  Fold 115g/4oz self raising flour and 3 tbsp cocoa powder into the mixture, then stir in 4 tbsp water and the finely grated zest of 1 orange.  Pour mixture into a lined 900g/2lb loaf tin and bake as above.

Meanwhile, remove the zest of 1 orange using a zester and blanch in three changes of boiling water.  Squeeze the juice of the orange into a pan, add 3 tbsp icing sugar and heat until the sugar has dissolved, then add the blanched orange zest and simmer for 3 minutes.  Prick the surface of the cooked sponge, pour over the hot syrup and leave to cool.