You've found a new cake:
This was originally called a 'surprise cake', and indeed that is a good name as the orangey tang of the sponge is completely unexpected. 'Jaffa Cake' is certainly more descriptive of what you are getting!
- 175 g unsalted butter (room temperature)
- 175 g golden caster sugar
- 2 orange zest
- 3 eggs (large)
- 175 g self-raising flour (sifted)
- 30 ml fresh orange juice
- 80 ml fresh orange juice
- 60 ml Cointreau
- 150 g plain chocolate (finely chopped)
- 55 g unsalted butter (cut into small pieces)
Beat the butter in a mixing bowl until pale and creamy. Add the sugar and orange zest and beat until light and fluffy. Gradually beat in the eggs, 1 tablespoon at a time, beating well after each addition. Using a large metal spoon, fold in the flour in 3 batches, adding the orange juice with the last batch of flour. Spoon the batter into the prepared tin and level the surface. Bake in the centre of the preheated oven for 35-40 minutes.
Whilst the cake is baking, make the orange syrup. Put the orange juice, liqueur and caster sugar in a bowl and, using a metal spoon, mix until the sugar dissolves.
When the cake is well risen, golden brown and a skewer inserted in the centre comes out clean, remove from the oven and transfer to a wire rack. Prick the cake all over and slowly spoon the syrup over the cake. Leave until cold before removing from the tin.
To make the icing, gently melt the chocolate in a bowl over steaming water. Remove the bowl from the heat, gently stir the chocolate until smooth, then spread it evenly of the top and sides of the cake. Let set, then transfer to a serving plate.
Store the cake in an air tight container and eat within 6days. The cake, minus the syrup and icing may be frozen.