Coffee walnut cake

After my successful attempt at making gingerbread, the next thing I wanted to tackle was coffee cake. I have absolutely no memories associated with coffee cake (though I cannot be sure I haven't had an indifferent version sometime in the past), but there is something about the name that cries out to be tried.
Found a recipe that looked good, halved the quantities, and just did it.

225g unsalted butter, plus extra for greasing
225g caster sugar
4 free-range eggs
50ml strong espresso coffee
225g self-raising flour
75g walnuts

Method

• Preheat the oven to 180C.
  In a bowl, beat the butter and sugar together until very light and pale.
  Add the eggs one at a time to the butter and sugar mixture, beating well to completely incorporate each egg before adding the next egg.
  Add the espresso to the mixture and stir well.
  Add the flour and walnuts and stir well to completely combine.
  Spoon the cake mixture into cupcake liners
• Transfer to the oven to bake 22-25 minutes, or until a skewer inserted into the centre of the cake comes out clean and the cake is golden-brown.
  Remove the cakes from the oven and leave to cool on a wire rack.