FOR THE SPONGE:
50g walnut pieces
225g caster sugar
225g soft unsalted butter, plus some for greasing
200g plain flour
2 1/2 teaspoons baking powder
1/2 teaspoon bicarbonate of soda
1-2 x 15ml tablespoons milk
1 espresso shot
I used our coffee machine to achieve this. Alternatively, if you wanted a more muted coffee flavour, you could just use 2 teaspoons instant coffee granules dissolved into a tablespoon of water.
FOR THE BUTTERCREAM FROSTING:
I actually just used the buttercream I had left over from my rainbow cake, but added a shot of espresso to give it the coffee flavour.
The ingredients of my buttercream frosting were:
350g icing sugar
175g soft unsalted butter
1 tbsp milk
(add the 1 espresso shot here)
It is possible to make this recipe using a food processor, but I prefer making it by hand.
Butter the 2 sandwich tins and line the base of each with baking parchment.
Bash the walnuts to a rubbly powder with a rolling pin and then mix with all the dry ingredients in a mixing bowl.
In a separate bowl, cream the butter and the sugar together until considerably lighter. Then add the eggs, one at a time, and then the dry ingredients, bit by bit. At this stage, add the coffee, which shouldn't be too hot as coffee that is too hot will melt the fat in the butter.
Divide the mixture between the two lined tins and bake in the oven for 25 minutes, or until the sponge has risen and feels springy to the touch.
While the cake is in the oven, you can make the buttercream.
Cool the cakes in their tins on a wire rack for about 1- minutes, before turning them out onto the rack and peel off the baking parchment.
Instead of using instant espresso powder, like it says in the original recipe, I made a shot of espresso from our Nespresso machine (which is pretty damn cool, by the way.)
I had never even tasted a coffee and walnut cake before, let alone made one, so I had no idea what it was meant to taste like. BUT IT TASTED GOOD, and I think that has to be a good sign, right?