Drain the peaches, reserving 15 cl of their syrup. Mix in the kirsch. Quickly dip the biscuits in this syrup and line the bottom and sides of a charlotte mold tightly, creating a sturdy base.
Soak the gelatin sheets in cold water until softened.
Whisk the egg yolks with sugar until pale and creamy. Gradually whisk in the boiling milk, then cook over low heat, stirring constantly, until the custard thickens and coats the back of a spoon.
Remove from heat. Gently fold in the softly whipped cream and half the coarsely chopped pistachios. Drain and stir in the softened gelatin to set the mousse.
Quarter the peaches, reserving 100 g for garnish. Layer the mousse and peaches into the mold. Refrigerate for at least 4 hours until firm.
Unmold the charlotte. Dust with icing sugar and decorate with reserved peach quarters, pistachio wedges, silver beads, mint leaves, and red fruits for a stunning finish.
