Soak gelatine in cold water. Mix quark, egg yolk, lemon peel, vanillin sugar and sugar (except for one tablespoon) in a bowl. Squeeze the gelatine, dissolve and stir into the quark mixture.
Cool until the mass begins to gel. In the meantime, beat the egg whites until stiff and allow the remaining sugar to trickle in. Fold the beaten egg whites into the quark cream and distribute in 4 moulds. Put in a cool place for at least 3 hours.
Sort the blackberries, put some aside for garnishing and puree the rest with juice, sugar and cinnamon. Pass through a sieve. Dip the moulds briefly in hot water and turn out the curd jelly onto plates.
Pour sauce around the jelly and garnish with blackberries and blackberry leaves.