A perfect celebration cake when you don't have time to make something elaborate.
Preheat the oven to 180°C. Cream the butter and sugar until light and fluffy. Stir in the chopped walnuts. Beat in the eggs, one at a time. Fold in the flour then add the coffee to create a thick batter - not too dry but not runny. Combine well. Spoon into a lined and greased springform pan (20cm) and bake until risen and golden. You may need to add foil over the top half way through to prevent it browning too much. Cake is cooked when a skewer comes out clean.
Combine softened butter and icing sugar mixture and add the coffee. Allow the icing to stand while cake is cooking so that it sets a little. Spread onto cooled cake and decorate with walnut halves. Serve with tea or coffee.