Pre-heat your oven to 170°c and line a six hole muffin tray with your muffin cases. Muffin cases make for much better cupcakes but if you want smaller cakes (say-what?!) you can use standard cupcake cases but you'll need to use more in total.
Sift the flour, cocoa powder, sugar, baking powder & salt into a large bowl and add the butter. Mix on a medium speed until you get a sandy consistency.
In a separate bowl whisk the egg, milk & orange zest before gradually adding it to the flour mixture, a little at a time.
Once both mixture are just combined (cupcakes don't need much mixing, so be gentle) use an ice cream scoop to fill the cases 2/3 full.
Bake for around 20 minutes until a skewer inserted comes out clean.
For the Icing
Mix the icing sugar & butter in a large bowl on a medium speed. Once combined add the golden sugar & orange extract.
(Optional) Add the orange food colouring gel to make the desired colour.
Pipe on your cooled cupcakes & finish with a wedge of Terry's Chocolate Orange. I used the miniature ones but the normal sized ones will be just as good.