Drain the pineapple and collect the juice. Put 1 slice aside. Coarsely chop the rest, puree with half of the yoghurt and 5 tbsp. juice. Stir in the remaining yoghurt
Whip cream until semi-stiff and season with vanilla sugar. Fold into the yoghurt just before serving. Pour into 4 glasses. Quarter the pineapple slice. Decorate cocktail with coconut flakes and pineapple