• For the cake:
  • 3 large eggs
  • 125 grams caster sugar
  • 100 grams plain flour
  • 25 grams cocoa powder
  • Ganache:
  • 200 grams milk chocolate
  • 50 grams butter
  • 100 milliliters double cream
  • Nutella buttercream:
  • 75 grams unsalted butter
  • 150 grams icing sugar
  • 2 tablespoons Nutella
  • 1 tablespoon milk


  1. Preheat the oven to 200C/fan180C/gas 6. Lightly brush the base of a 33 centimeters x 23 centimeters Swiss roll tin with vegetable oil and line with baking parchment.
  2. Put the sugar and eggs into a large bowl or the bowl of a stand mixer and whisk with an electric whisk for 8-10 minutes, until pale and thick enough for the mixture to leave a trail when the whisk is lifted.
  3. Sift the flour and cocoa powder into the mixture and fold in very carefully until no traces of flour are left.
  4. Pour the mixture into the prepared tin and use a spatula to smooth it evenly into the corners. Bake in the centre of the oven for 10-12 minutes, until golden and
  5. Risen and just firm to the touch.
  6. Whilst the sponge is baking, make the buttercream by creaming the butter and sugar together using an electric whisk, then beating in Nutella and milk.
  7. Lay a piece of greaseproof paper that is larger than the sponge on top. Dust the greaseproof paper with caster sugar and turn the cake out onto it. Use a
  8. Serrated knife to cut away strips 1/3 the way down then roll and allow to cool.
  9. Unroll and cover with the buttercream, slicing the cake strips up to create feet. Place into the fridge for 30 minutes to set.
  10. For the Ganache: place the cream and butter into a small saucepan and heat until steaming. Stir in the chopped chocolate until the mixture is smooth. When the cake roll is set, transfer to a wire rack and pour the ganache over the top. Allow to set for 10 minutes, then cover with rainbow smarties. Make the caterpillar face by melting and piping white chocolate, using smarties for the eyes and mouth. Top with candles and celebrate!