Pistachio and chocolate stripe cake

Method

• step 1

  Heat the oven to 180C/fan 160C/gas 4. Measure the ingredients for the sponge in 3 batches (4 eggs, 120g sugar, 80g flour, 40g pistachios and 40g butter). Line a 21 x 31cm baking tray or tin with non-stick baking paper.

• step 2

  Whisk one batch of eggs and sugar together until they are light and fluffy and almost mousse-like, this will take about 5 minutes. Fold in the flour and pistachios followed by the butter. Spoon the mixture into the tin and level it out. Bake for 12 minutes, or until the sponge is springy and cooked through, but still pale in colour. Leave to cool for 3 minutes and then carefully invert the cake onto another piece of baking parchment that has been dusted with caster sugar, peel off the top layer of parchment, and lay it back on top lightly. Roll up the sponge and leave it to cool rolled up. Repeat with the other two batches of sponge but leave these two to cool flat.

• step 3

  Put all the frosting ingredients in a pan and heat gently until you have a shiny, smooth mixture. Leave to cool until it is thicker but still spreadable.

• step 4

  Cut each of the flat sponges in half (exactly down the centre) to make two long strips. Unroll the rolled up sponge and do the same. Trim any woggly edges off the sides but try and keep all the strips exactly the same size. Lay one of the strips that had been rolled up on a piece of parchment and spread a thin layer of frosting all over it. Lay the other rolled piece on top but 2cm inwards from the short edge, roll them up, folding the bottom piece up and over the top one to get the roll started. When you have a roll, lay another strip down, frost it and join it edge-to-edge onto the roll where the outside strip ends. Repeat until you have used all the strips, then upend the roll onto a cake board and make sure the top is flat, trim it if you need to. Warm the frosting a little until it is shiny and soft enough to spread easily, then frost the outside of the cake.