Preheat your oven to 180 degrees and put paper cases in a muffin tin.
Cream the butter and sugar together until light and fluffy (I used a hand mixer).
Add the eggs one by one, mixing after each addition, and then fold in the flour, baking powder and salt.
Add the coffee and milk and mix gently.
Spoon the mixture into the cases, ensuring they are no more than two thirds full.
Bake for 14 to 18 minutes until golden.
Put the cakes on a cooling rack and allow to cool.
Make the icing by creaming together the softened butter and icing sugar until soft and fluffy and it has turned pale. Add the coffee and mix through well.
Put the icing in a piping bag and pipe a swirl on top of each cake. If you have them, decorate with a chocolate coated coffee bean.