For the chocolate cream, heat 500 g cream in a pot. Divide 300 g chocolate into pieces and melt in the cream. Let it cool down first, then put it in a cool place for about 3 hours.
For the sour cream, stir the pudding powder, 3 tbsp. sugar and approx. 100 ml milk until smooth. Bring the rest of the milk to the boil, stir in the pudding powder, bring to the boil again and simmer for about 1 minute while stirring. Cover with foil and let cool off.
For the sponge cake, whisk eggs and 75 g sugar until creamy. Mix flour and baking powder and fold in. Spread the sponge mixture on a greased and flour-sprinkled fat pan (approx. 32 x 39 cm). Bake in a preheated oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer) for approx. 12 minutes. Let them cool down.
Whip the chocolate cream briefly (see tip below), spread on the sponge cake and smooth it down. Chill for about 10 minutes.
For the sour cream, stir the pudding with the whisk of the mixer until smooth. Stir in the sour cream, vanilla sugar and cream setting agent and whip for approx. 1 minute. Spread on the chocolate cream and chill for another 10 minutes.
For the glaze, heat 300 g of whipped cream in a pot. Divide 300 g chocolate into pieces, chop coconut fat and melt both in the cream. Let it cool down a little.
Peel the bananas, cut them in half lengthwise and sprinkle them immediately with lemon juice. Dab the bananas slightly dry and place them with the cut surface on the sour cream, pressing slightly. Pour chocolate icing on top and chill for about 4 hours.
Too big? If the baking tray does not fit in the refrigerator, cut the base in half lengthwise and place it on two trays. Then place a rail made of aluminium foil folded several times around each tray.
Creamy: Whip the chocolate cream for only about 1 minute with the whisk of the mixer. Otherwise it will be too firm and cracked.