Battenberg cake

Method

• step 1

  Heat the oven to 180C/fan 160C/gas 4 and butter the sides and bottom of a 20cm square tin. Cut a 20cm × 40cm piece of baking parchment and the same of foil. Butter the foil and then put the baking parchment on top so that they’re stuck together.

• step 2

  With the foil-side facing up, fold in half widthways like a book, then open out, turn over and push up the centre fold to make a 4cm pleat, that sticks up, down the centre.

• step 3

  Line the base of the tin with the foil-side down, ensuring the pleat is uppermost and is dead in the centre of the tin, to create 2 identical rectangles within the tin. Ensure the paper-lined foil is pushed into all the corners of the tin with a slight overhang on either side.

• step 4

  Put the flour, sugar, butter, eggs and baking powder in a bowl and whisk until just combined. Divide the mixture between two bowls. Whisk the lemon zest into one plus enough colouring to make a strong custard colour. To the other, add the orange zest and enough colouring to make quite a bright orange colour.

• step 5

  Spoon each mixture into seperate halves of the tin. Make sure the divider is straight before smoothing the surface of each.

• step 6

  Bake in the oven for 25 minutes until the cakes have risen and are springy to the touch. Allow to cool for a few minutes before turning out onto a cooling rack and removing the divider.

• step 7

  Meanwhile, make the icing by beating together the butter, icing sugar, thyme, zest and juice until fluffy and smooth.

• step 8

  Trim the brown off long edges of the cakes and then cut each cake into 3 lengthways, ensuring all 6 strips are the same size and shape so that the cross section of each is a square.

• step 9

  Put a lemon, orange and then another lemon strip next to each other and use the icing to stick them together. Spread some more icing over the top and then stick the 3 remaining strips on top, alternating them in a chequerboard effect icing in-between them and on top.

• step 10

  Roll the marzipan out, on a clean worksurface dusted lightly with icing sugar, to a rectangle 20cm × 30cm or the same length as the cake and 4 times its width with a little extra to trim away.

• step 11

  Invert the cake onto the marzipan, iced-side down and 2cm in from the edge. Spread the remaining icing over the rest of the cake, apart from the chequerboard ends.

• step 12

  Carefully roll up the cake in the marzipan and seal where the marzipan joins. Trim any ends off to neaten.

• step 13

  Put the cake, seal-side down on a plate. Crimp the two top edges and score a diamond pattern on the top using the back of a knife before serving.