Preheat the oven to 180’C and place 12 cupcake wrappers into a 12 hole cupcake tin.
Beat together the butter and sugar until pale and creamy.
Add the eggs, one at a time, beating to combine after each one.
Sift in the flour and the cocoa power and then fold the mixture together with the orange zest and the chocolate chips.
Divide the mixture between the 12 cases and bake in the oven for 20-25 minutes until springy to touch.
While the cupcakes are baking whisk together the ingredients for the icing until smooth.
Cool the cupcakes on a wire rack and once cool ice the cup cakes and decorate with whatever you think will look pretty and taste delicious.