Rinse the cranberries. Bring the currant jelly to the boil in a small saucepan and cook the cranberries for 2 min. Remove the berries with a skimmer and cool.
Cook the currant jelly at low temperature until syrupy, cool a little, then stir with 1 tablespoon of slivovitz and set aside to cool.
Rinse the plums and grapes, cut them in half, remove the seeds or pits and mix. Season the fruit with cinnamon, add the remaining slivovitz and chill thoroughly.
For the sauce, beat the egg yolks with the powdered sugar until very creamy. Fold in yogurt and set aside to cool.
Whip the cream until stiff and carefully stir in the yogurt cream (do not stir).
Mix the plum salad with the cranberries, arrange on plates and garnish with the walnuts.
Pour the sauce and currant syrup on top or offer separately.