Grease and line the bottom and sides of a 20"x20" tin. Fold a piece of foil and baking paper the same size of the tin then place in the centre of the tin to create a divide.
Beat butter and sugar until light and fluffy, then add ground almonds, eggs, and flour then mix well. Add vanilla.
Divide the mixture into two separate bowls, add the almond extract and amaretto to one bowl and pink food colouring to the other.
Place mixture in tin, pink on one side, and plain on the other. Level the top and bake for 25-30 minutes or until skewer comes out clean.
Once cooled, level sponges, trim edges, and cut into two equal pieces so you have two plain and two pink sponges exactly the same size.
Roll out marzipan.
Heat jam slightly and using a spatula, smooth the jam on top and sides of one plain piece of sponge and stick one pink sponge to the side of it. Top with pink sponge in the same way then the final plain almond sponge so you have a checkered effect.
Smooth a thin layer of jam all over the long sides, then wrap the sponge in the marzipan, leaving the seam at the bottom.
Neaten edges by trimming and pinch the top edges to decorate.