Preheat your oven to 180ºc/160ºc fan and line a 2lb loaf tin.
Beat together the unsalted butter and sugar until light and creamy.
Add in the flour and eggs and beat again. Add the dissolved coffee and mix.
Stir through the chopped walnuts and pour into a lined tin. Bake the cake for 55-65 minutes.
Once baked, leave to cool fully.
Beat the unsalted butter on its own to loosen.
Add the icing sugar and beat together.
Add the dissolved coffee and mix.
Add the buttercreams to a piping bag and decorate.
Add some chopped walnuts and sprinkles and ENJOY!
