Preheat your oven to 180°C (350°F). Grease a 20cm square tin and create a divider down the center using foil lined with baking parchment to separate the two batters.

In a large bowl, cream the butter and sugar together until pale and fluffy, then beat in the eggs one by one.

Fold in the self-raising flour and ground almonds until the batter is smooth, then divide the mixture equally into two separate bowls.

Stir the cocoa powder into the first bowl to create the chocolate batter. Stir the orange zest and food coloring (if using) into the second bowl.

Spoon the batters into the separate sides of the prepared tin and bake for 25-30 minutes until risen and a skewer comes out clean.

Allow the cakes to cool completely in the tin, then remove and trim the edges to create two neat rectangular blocks. Slice each block lengthwise to create four long, equal strips.

Warm the apricot jam in a microwave or small pan, then strain it to remove any lumps.

Brush the long sides of the cake strips with jam and assemble them into a checkerboard pattern (one chocolate and one orange on the bottom, with the alternating colors on top).

Roll out the marzipan on a surface dusted with icing sugar until it is wide enough to wrap around the cake.

Brush the remaining jam over the marzipan, place the cake in the center, wrap the marzipan tightly around it, seal the seam, and trim the ends for a neat finish.