coffee and walnut cakerating:
175g unrefined golden caster sugar
65g walnut pieces
3 large eggs
175g self-raising flour
1 tsp baking powder
2 tsp instant coffee granules
For the filling:
400g icing sugar
2 tsps instant coffee granules
60g walnut pieces
Preheat the oven to 180°C/gas mark 4, and line the base of two 21cm sponge tins with greaseproof paper
Beat the butter and sugar till it is light, pale and fluffy - you'll be wanting an electric mixer for this. Chop the walnuts. Crack the eggs into a bowl, break them up with a fork and add them a little at a time to the butter and sugar, beating well after each addition.
Mix the flour and baking powder together and stir into the butter and sugar gently, with the mixer on a slow speed or by hand, with a large metal spoon. Dissolve the coffee granules in 1 tbsp boiling water, then stir into the cake. Fold the chopped walnuts gently into the cake.
Divide the cake mixture between the two cake tins, smooth lightly, and bake for 20-25 minutes.
To make the frosting, beat the butter till soft and pale with an electric beater, then add the sugar and beat till smooth and creamy. Stir 1 tbsp boiling water into the coffee granules then mix it into the buttercream. Fold in the walnut pieces.
As soon as it is cool, turn one half of the cake upside down on a plate or board, spread it with a good third of the buttercream, then place the second half on top. Spread the remaining buttercream on top and round the sides.