Grease a fat pan (approx. 32 x 39 cm; at least 3.5 cm deep) and dust with flour. Break chocolate into pieces and melt in a hot water bath. Allow to cool down a little
Separate eggs. Mix butter and sugar until creamy. Gradually stir in the liquid chocolate. Stir in the egg yolks one by one. Mix flour, baking powder and cocoa and stir in portions
Beat the egg whites and 1 pinch of salt until stiff, adding icing sugar. Stir 1/3 beaten egg white into the dough, fold in the rest
Spread on the fat pan. Bake in the preheated oven (electric oven:175 °C/circulating air: 150 °C/gas: level 2) for approx. 25 minutes. Let them cool down
Divide the base into 4 pieces and cut through 1x horizontally. Warm up the jam and pass it through a sieve. Spread approx. 1/3 of the jam on the lower shelves, place the upper shelves on top. Cut each piece into approx. 6 slices (approx. 5 x 10 cm)
Coarsely chop the dark chocolate coating and melt in a hot water bath. Cover the cuts on the underside with some of this. Dry for about 20 minutes. Then spread the rest of the jam all around, up to the bottom. Leave to dry for approx. 20 minutes. Melt the rest of the dark chocolate again. Cover the slices with it. Leave to dry for about 40 minutes. Chop the milk chocolate, melt it, put it into a plastic bag and cut off a small corner. Decorate the slices with it and let them dry.