Preheat your oven to 190C/170C(fan)/375F/gas mark 5 and line a 12-hole muffin tin with paper cupcake cases.
Sift together the flour, bicarbonate of soda, caster sugar and brown sugar together. Set aside.
Make a strong cafetiere of Percol coffee. Measure out 115ml and add to a small saucepan along with the goat's butter and cocoa powder. Gently heat until everything has melted. Do not allow to boil.
Measure out the A2 milk in a measuring jug. Add the vinegar and stir. Crack in the egg and add the vanilla.
Add the cooled coffee chocolate mixture to the dry ingredients along with the milk mixture. Stir well to combine. The batter will be thin.
Spoon into the prepared cupcake cases.
Bake in the centre of the oven for 20 minutes, until well risen. A skewer inserted in the centre of the cupcakes will come out clean when they are done.
Transfer to a wire rack to cool completely.
To prepare the frosting, beat the butter and icing sugar together until well combined. Divide the frosting in half (400 grams in two bowls).
Add the cocoa powder and milk to one half and beat well until light and fluffy. Add the cold coffee to the other half, beating well.
When the cupcakes have cooled, place a large star nozzle into a large piping bag. Carefully spoon each frosting into either side of the piping bag (or use a dual icing bag) and pipe large swirls of frosting on top of each cupcake.
a2 Milk™ is not suitable for cows’ milk protein allergy.
If you have been medically diagnosed with any milk intolerance, seek advice from your doctor before use.
Mum of three, daydream adventurer, OU Life Sciences graduate, occasional crafter, ex-pat Canadian & quite possibly Britain's most northerly food blogger.