Coffee and Walnut Sponge Cake

A delicious gluten-free sponge flavoured with coffee and walnuts, topped with a rich coffee icing that is made on the hob.


This gluten-free coffee and walnut cake is a real favourite in our household. There is something particularly nice about the combination of coffee and walnuts. Strangely I don't even drink coffee, yet I love the subtle coffee flavour in this cake! It isn't too strong but just combines with the light fluffy sponge, walnuts and rich coffee icing to make a deliciously flavoured cake.

The icing is made by heating all the ingredients together in a saucepan on the hob. It makes a deliciously rich and unctuous icing that sets with a smooth sheen and cracks gently as you cut it.

Gluten-free coffee and walnut sponge cake topped with coffee icing and caramelised walnuts

Gluten-free coffee and walnut sponge cake topped with coffee icing and caramelised walnuts

Ingredients

Makes a 20cm cake

You will need 2 x 20cm/8" cake tins

For the cake:

  • 175g butter or margarine
  • 175g caster sugar
  • 175g gluten-free self-raising flour
  • 3 eggs
  • 1½ tsp baking powder
  • 2 tsp instant coffee
  • 100g chopped walnuts
  • 1 tbsp milk

For the coffee icing:

  • 100g butter
  • 400g icing sugar
  • 1 tbsp milk
  • 1 tsp instant coffee

For the caramelised walnuts:

  • 50g sugar
  • 50g walnut pieces

Method

  • Preheat oven to 180°C/160°C fan/350°F/gas mark 4.
  • Dissolve the coffee in 1 tsp hot water and allow to cool slightly.
  • Cream together the butter and sugar until soft and fluffy. I like to use a food processor or stand mixer to make this cake, but you can make by hand.
  • Crack the eggs into a mug one at a time and whisk with a fork.
  • Add the eggs to the butter mixture with the flour and baking powder.
  • Mix.
  • Add the dissolved coffee mixture and 1 tbsp milk to the mixture and mix well until smooth.
  • I like to beat for around 3-4 minutes in the food processor with the whisking tool.
  • Stir in the walnuts by hand, until evenly distributed.
  • Spoon into two greased and lined 20cm/8" cake tins.
  • Bake for 25-30 minutes until the top of the cake springs back when touched, and a knife is clean when you put it in the cake.
  • Cool on a wire rack.

To make the caramelised walnuts:

  • Line a baking tray with baking parchment.
  • Heat the sugar gently until it bubbles and turns to liquid.
  • Stir in the walnuts making sure they are covered in the sugar and then tip onto the baking parchment, separating if you can, and allow to cool.

To make the coffee icing:

  • Put all the ingredients in a saucepan and heat gently on the hob, stirring frequently.
  • Once the butter is melted, stir the whole time until the icing is well mixed and combined.
  • Allow to cool slightly and then spread a third of the buttercream over one of the cakes and sandwich together.
  • Cover the top of the cake with the rest of the icing.

To serve:

  • Add the cooled caramelised walnuts to the top of the cake just before serving.

I find that sometimes if the caramelised walnuts are on the cake for too many hours before serving, the caramel can become runny again so I only add them just before serving.

If you have walnut halves they look really great caramelised, but I usually just buy walnut pieces as they are much cheaper and think they look almost as good.