Mix flour, cocoa, baking soda and baking powder. Mix eggs, oil, buttermilk, 1 pinch of salt and sugar with the whisk of the hand mixer. Add the flour mixture in portions and mix to a smooth dough.
Grease 3 springforms (each 20 cm Ø) and dust with flour. Fill each springform pan with approx. 1/3 of the dough, smooth it down. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for about 30 minutes.
After about 15 minutes cover the cake with foil. Remove and let it cool down on a cake rack. Alternatively, bake the 3 cake layers one after the other.
For the pineapple blossoms, peel the pineapple so that the seeds are completely removed. Slice off approx. 12 very thin slices of the pineapple (approx. 20 g each). Use the rest of the pineapple for other purposes.
Place the pineapple slices close together on a baking tray lined with baking paper and bake in a preheated oven (electric cooker: 150 °C/ circulating air: 125 °C/ gas: see manufacturer) for approx. 25 minutes until the edges turn golden yellow.
Meanwhile, chop the chocolate and melt it over a warm water bath, stirring occasionally. Take off and let it cool down. Mix icing sugar, butter, nut nougat cream, sour cream and 1 pinch of salt with the whisks of the hand mixer to a smooth cream, add the still liquid chocolate in a thin stream and stir in.
Chill the cream for 20-30 minutes.
Remove pineapple slices from the oven, place them in the recesses of a muffin baking tray (12 recesses each), press them in slightly. Bake in the preheated oven (electric cooker: 65 °C/ convection oven: 40 °C/ gas: see manufacturer) for approx. 1 hour or allow to dry.
Then carefully lift the flowers out of the hollows and let them cool down.
In the meantime, remove the cake bases from the moulds and cut the surfaces straight. Place a cake ring around one base. Halve the chocolate cream. Put one half of the cream in a cool place. Spread about half of the remaining cream on the cake base, smooth it down.
Place the second cake layer on top, add the remaining cream, smooth it down and cover with the third cake layer. Chill for about 1 hour.
Remove the cake from the cake ring. Stir the rest of the chocolate cream again and spread the cake all around. Decorate the cake with pineapple blossoms and sugar pearls.