Grease the springform pan (26 cm Ø). Pour yoghurt into a bowl. Wash 1 cup, dry it and take to measure
Mix flour, cocoa, baking powder and sugar. Add eggs, oil and milk. Stir everything briefly. Pour into the mould. Bake in the preheated oven (electric cooker: 175 °C/circulating air: 150 °C/gas: level 2) for about 15 minutes. Let cool off
Close the cake ring around the base. Soak the gelatine in cold water. Peel and slice 3 bananas, sprinkle with 2 tbsp. juice. Squeeze the gelatine, dissolve at low heat. Stir in 3 tbsp yoghurt, then stir into the rest of the yoghurt. Whip the cream until stiff, sprinkle with vanillin sugar. Fold into the yoghurt. Spread 4 tbsp. yoghurt cream on the base. Place banana slices on top. Spread the rest of the cream on top. Chill for about 4 hours.
Peel 1 banana, cut into slices. Sprinkle with 1 tbsp. juice. Fill chocolate chips into a freezer bag and seal. Melt in hot water and cut off a small corner. Decorate the cake with chocolate strips, banana, jelly bananas and pistachios