Preheat your oven to 180C/160C Fan, and line three 8"/20cm cake tins with parchment paper. Leave to the side for now!
Beat your Butter and Sugar together until light and fluffy!
Add in the Flour, Cocoa Powder, Eggs, and Orange Zest and beat until smooth!
Split evenly between the three tins, and bake in the oven for 25-30 minutes.
Check its cooked by using a skewer, it should be clean! Leave to cool in the tins for 10 minutes, and then on a wire rack to cool fully.
For the Frosting!
Make sure your Unsalted Butter is at room temperature.
Beat the butter until its smooth and supple, and gradually add in your icing sugar.
Whilst doing this, melt your DARK Terry's Chocolate Orange carefully until smooth!
Beat the Butter and Icing Sugar for a few minutes until its really lovely and smooth.
Add in your melted Dark Terry's Chocolate Orange and beat again. If the mix is a bit hard, or way too thick, add in 1-2tbsp of boiling water. Don't do this straight away, make sure you beat the buttercream first as it might not need it.
Once all together, don't beat for too long or it might split.
For the Decoration!
Get your first layer of cake, and pipe little dollops of Buttercream onto it. I do this with a large round nozzle, piping directly downwards!
Do this all over, and then add the second layer, and repeat. Add the third layer of cake, and pipe the rest of the Buttercream on top! I do it all over, then add another ring to sandwich the Slices between.
I put 21 segments on top and alternated two Milk Chocolate slices and one Dark Chocolate slice all the way around to use up the rest of the second Dark Terry's Chocolate Orange, but you can do what you want.
Sprinkle over your fave sprinkles, and enjoy!
The Dark Terry's Chocolate Orange is much better to use for the Buttercream compared to the Milk!