Defrost the mixed fruits and cut the peaches into small pieces. Sprinkle the prepared fruits with rum and let them steep for about 30 minutes
If desired, remove about 4 tablespoons of the fruit and puree. Stir smooth with quark and season with sugar. Whip cream until stiff. Let vanillin sugar trickle in. fold cream into the fruit quark
Arrange the quark cream with the remaining fruit. Decorate with wafer rolls