Method

• 1.
  Preheat the oven to 180°C/350°F/Gas Mark 4. Lightly grease a 26 x 16.5 cm/10 x 6½ inch cake pan with butter and line the bottom and sides with baking (parchment) paper. Using a piece of aluminium foil, create a divider in the centre of the pan by folding the aluminium foil over itself several times, ensuring it divides the pan widthwise in a straight line.
• 2.
  Put a medium saucepan of water over a medium heat. Put the eggs and 25 g/¾ oz (2 tablespoons) of the sugar into a metal bowl and set the bowl over the pan of water, making sure the bottom of the bowl doesn’t touch the water. Whisk the eggs and sugar together for 5–7 minutes until pale and smooth. Meanwhile, put the butter and the remaining sugar into a stand mixer fitted with a paddle attachment and beat until pale and aerated.
• 3.
  Once both mixtures are pale and aerated, slowly add the egg to the butter mix, then gently fold in the sifted flour until the batter is completely smooth. Divide the batter into 2 equal quantities, adding 3–4 drops of food colouring to one part. Mix thoroughly, then spoon both mixes into opposite sides of the prepared pan. Bake in the centre of the oven for 25 minutes, turning halfway through. Remove from the oven and leave to cool in the pan for 5–10 minutes before turning out and leaving to cool completely on a wire rack.
• 4.
  To assemble the cake, cut the sponge in half and, separating the different colours, trim the sides and top of each, creating 2 even rectangular strips of sponge, then slice in half lengthwise. Form 4 individual bands of sponge, 2 of each colour, about 13 cm/5 inches long, 3 cm/1 1/4 inches high and 4 cm/1 1/2 inches wide. The bands must be even in proportion.
• 5.
  Heat the apricot jam in a small saucepan over a low heat for a few minutes until warm, then brush it over 2 sides of each piece and sandwich them together, creating a chequered pattern. Once they are firmly stuck together, knead and roll out the marzipan into a rectangle, 30 x 16 cm/12 x 6¼ inches with a little icing (confectioners’) sugar to about 2 mm thick. Brush the marzipan with apricot jam, then put the sponge at one end, applying a little pressure, and gently roll the sponge, ensuring the marzipan doesn’t tear. Press the edges so that it seals, then carefully trim the excess marzipan where the seam overlaps. Gently smooth the marzipan using the palm of your hand to remove any air pockets and leave to chill in the fridge for 1 hour before serving.