• 

  walnuts roughly chopped

  75 g
• 

  unsalted butter room temperature, cut into pieces (2 cm)

  125 g
• 

  milk

  125 g
• 

  natural yoghurt

  180 g
• 

  egg

  1
• 

  vanilla bean extract

  1 tsp
• 

  instant granulated coffee

  1 tsp
• 

  self-raising flour

  300 g
• 

  caster sugar

  125 g

Buttercream icing

• 

  boiling water

  1 tbsp
• 

  instant granulated coffee

  2 tbsp
• 

  butter room temperature, cut into pieces (2 cm)

  175 g
• 

  icing sugar

  190 g
• 

  chopped walnuts to decorate

  2 tbsp
• 

  milk chocolate chips to decorate

  1 tbsp