piece of cardboard in the fold, sellotape to create an upright perpendicular divider. Now grease the tin and line with the divided compartments.
Using an electric mixer, cream the butter and sugar together until pale and fluffy.
On a slow whisking speed, gradually add in the eggs, one at a time. Stir in the vanilla essence. Gently fold in the flour until fully incorporated. Divide the mixture in half into two separate bowls ( weigh each half for equal quantities of batter).
Insert a clean skewer into the food colouring ( paste or gel) and add to one half of the mix to give a strong pink colour. Leave the batter in the second bowl plain.
Pour batters into separate sides of the tin. Bake in a preheated oven for 20- 25 minutes or until slightly risen and a skewer inserted into the centre comes out clean.
Transfer the cake to a wire rack to cool. Use a serrated knife to cut the sponge into four neat long fingers equal in size. While matching up opposite colours, trim away uneven edges to ensure they fit together as a square block.
To assemble, heat the jam and sieve it to remove any lumps. Gently spread the jam along the edges of the cake slices being joined together. Press the pieces together firmly.
To wrap in marzipan, dust icing sugar over a sheet of parchment paper on a work surface. Thinly roll out a rectangle of marzipan ( four times the width of the cake). Spread jam over one length of the cake and position the jam- covered side on the marzipan to one side of the rectangle. Spread more jam over the remaining long sides and firmly roll the cake over towards the opposite edge, keeping the edges square while wrapping it tightly in the marzipan.
Trim and form a neat seam under the base of the cake. Slice either end to expose a delightful cross- section of the colourful squares. Try different flavourings of the sponges. Add 1/ 2 tsp almond essence to the plain sponge mixture or freeze dried raspberry powder to the pink sponge ( which will also substitute as a natural food colouring).