Drain the pineapple slices well on a sieve (collect the juice, use it for other purposes). Put the baking mixture into a mixing bowl. Add soft fat, eggs and 100 ml milk.
Use the whisks of the hand mixer on the highest setting to work into a smooth dough in approx. 3 minutes. Grease the baking tray and spread half of the dough on top. Stir the remaining milk and cocoa mixture (enclosed in the package) into the remaining dough and spread it on the light-coloured layer of dough.
Mix the layers of dough with a fork and smooth them down again. Cover with pineapple. Pinch a firm rail from aluminium foil and place it in front of the dough. Bake the cake in a preheated oven (electric: 175 °C/ gas: level 2) for 25-30 minutes.
Let it cool down on a cake rack. An advocaat cream tastes very good with it. Makes about 16 pieces.