Vanilla foam: Bring the whipped cream and milk to the boil in a saucepan while stirring. Add half of the sugar. Scrape the vanilla pulp from the pod and simmer for about 3 minutes. Remove the pod with a spoon. Beat the yolks with the whole egg and the remaining sugar in a bowl with a whisk until creamy. Slowly stir the egg foam into the hot vanilla mixture in a boiling water bath until it forms a bound, thick cream. Pour into a bowl and set aside to cool.
Stir in between to prevent skin from forming. Skin peaches (if skin comes off badly, dip briefly in hot water with a spoon), pit and quarter. Put them in a suitable bowl.
Mix juice of one lemon with maraschino and sugar and drizzle over peaches. Place in the refrigerator and let stand for about 1 1/2 hours. Turn to the other side in between.
Just before serving, arrange 2 peach pieces each on a dark plate. Whip egg whites to stiff peaks and fold into custard. Carefully whisk until creamy. Pour 3 tbsp vanilla bean sauce around each peach and decorate with a leaf of lemon balm.
Serve immediately.