Preheat the oven to 180 °C top/bottom heat.
Melt the butter for the sponge cake. Sieve the flour and starch. Beat the sugar, eggs, salt and lemon zest in the bowl of a food processor for 7-8 minutes until frothy.
Carefully fold in the flour mixture first, then the butter. Spread the sponge mixture onto a baking tray lined with baking paper and bake in the middle of the oven for 12-15 minutes until golden brown.
Turn out onto a sheet of baking paper, remove the top sheet of baking paper and leave the sponge to cool completely.
Cut off the edges of the sponge generously and in a straight line to create a rectangle measuring approx. 30 × 20 cm.
Cut the sponge cake in half and roughly dice the sections.
For the filling, roughly chop the chocolate and melt in a metal bowl over hot steam.
Add the cocoa, fruit spread, rum, vanilla pulp, lemon juice and biscuit cubes and mix everything well.
Blitz the mixture in a food processor using the pulse setting until a homogeneous mixture is obtained.
Spread half of the remaining fruit spread evenly on each sponge cake rectangle.
Now spread the filling evenly on one sponge cake rectangle, place the second rectangle on top and smooth the edges of the filling.
Weigh down with a board and leave to stand for about 1 hour.
Place baking paper under a cake rack. Use a knife to cut the filled sponge cake into squares about 3-4 cm in size and place them on the rack with sufficient space between them.
To finish, heat the punch glaze according to the instructions on the packet, stir until smooth and pour over the punch doughnuts.
Leave the icing to dry.
Roughly chop the chocolate, melt in a metal bowl over hot steam and pour into a disposable piping bag. Cut off a small corner of the bag to create a very small hole. Decorate the Punschkrapferl with the chocolate and finish with a candied cherry.