Drain the peaches (possibly use the juice for other purposes)
Mix mascarpone and yoghurt with vanillin sugar, sugar and lemon peel until smooth
Coarsely chop the couverture with a knife and melt in a hot water bath
Cut the peaches into small cubes and put them into dessert glasses, except for 4 tablespoons. Spread the mascarpone-yoghurt cream on top. Add the remaining peach cubes
Use a spoon to draw melted couverture in decorative threads over the cream. Place the dessert in the refrigerator for about 30 minutes. Decorate as desired with lemon balm leaves