Topping: Juice of 1 orange 2oz/50g dark chocolate-melted
Method Preheat the oven to 180C/350F/Gas Mark 4. Grease and line an 11x7 inch oblong tin with parchment paper. Place the butter, sugar and orange zest into the electric mixer and beat for 3-4 minutes until it has a pale creamy consistency. Beat in the eggs and then sift in the flour and beat for another 2-3 minutes. At this stage beat in the chocolate chips until combined
Transfer into the prepared cake tin and bake in the oven for 30-35 minutes or until a skewer inserted in the centre comes out clean. Once the cake comes out of the oven, pour the juice of the orange on top of the cake and then after 10 minutes, carefully remove from the tin. Allow to cool on a wire rack.
Once the cake is cool drizzle it, in your preferred pattern, with the dark chocolate to create somewhat of a marbled effect on the top of the cake. Garnish if desired with orange segments. Dust with icing sugar.