Mix in butter until fluffy, stir in the strongly chopped marzipan, sugar, egg white, vanilla sugar and lemon zest, finally stir in flour; Pour the mixture into a piping bag with a serrated nozzle; Splash on mussel-like swabs (not too big - after baking, 2 should be put together to make a biscuit!); bake lightly at 160 ° C; let cool down; Put two of them together with jam (any other jam can of course also be used), dip half in chocolate icing, let dry. Excellent Christmas cookies! Even those who don`t normally like marzipan should give it a try.