Drain mandarins and reserve a small amount of juice. Distribute mandarins between 4 dessert glasses.
Crumble biscuits. Mix quark and cream cheese until smooth with sugar, vanilla sugar and 1-2 tablespoons of tangerine juice. Pour into dessert glasses. Beat cream until stiff and fold in 2 tablespoons of grated chocolate and biscuits. Top dessert glasses with cream and serve garnished with remaining grated chocolate and petals.