Preheat your oven to 180°C (350°F). Grease an 8-inch square cake tin. Create a divider in the center of the tin using a piece of folded parchment paper and foil. This allows you to bake both colors of batter in one tin without them mixing.
In a large mixing bowl, cream together the softened butter and caster sugar until the mixture is light, pale, and fluffy. Beat in the eggs one at a time, adding a tablespoon of flour with each to prevent the mixture from curdling. Gently fold in the remaining flour, ground almonds, and almond extract until just combined.
Divide the batter equally into two bowls. Leave one bowl plain for the light color. In the second bowl, add a few drops of red or green food coloring gel. Stir gently until the color is vibrant and even throughout the batter.
Spoon the plain batter into one side of the divided tin and the colored batter into the other. Level the tops with a spatula. Bake for 25 to 30 minutes, or until the sponges have risen and a skewer inserted into the center comes out clean. Let them cool completely on a wire rack.
Once cooled, trim the tops of the cakes to make them perfectly flat. Cut each cake into two long, equal-sized rectangular strips. You should now have four strips in total—two plain and two colored. Use a ruler to ensure they are all the same width and height.
Brush the sides of the cake strips with warm, strained apricot jam. Stick them together to create a 2×2 checkered pattern (a plain strip next to a colored strip, with the opposite colors stacked on top). Press them together firmly so the jam acts as a glue.
Roll out the marzipan on a surface lightly dusted with powdered sugar into a rectangle large enough to wrap around the cake. Brush the outside of the assembled cake with more jam. Place the cake on the marzipan and roll it up tightly. Trim any excess marzipan and press the seam to seal it at the bottom.