Drain the pineapple on a sieve. Cream 200 g sugar, vanillin sugar and soft fat. Stir in eggs bit by bit. Mix flour, salt and baking powder, sieve over it and stir in briefly.
Gradually stir in 5 tablespoons of milk. Grease the baking tray (35x40 cm). Spread half of the dough on it. Stir cocoa powder, 25 g sugar and remaining milk until smooth and add to the remaining dough.
Spread on the light layer of dough. Pull through spirally with a fork and smooth again. Spread pineapple rings evenly on the dough. Bake the cake in a preheated oven (electric: 175 °C/ gas: level 2) for approx. 30 minutes.
Leave to cool and decorate with mint leaves if necessary. Makes about 16 pieces.