Pour milk into a mixing bowl. Stir in the sauce powder with a whisk, stir vigorously for approx. 1 minute, refrigerate. Put 100 ml water and 75 g sugar in a pot, bring to the boil.
Let simmer for 5 minutes at high heat. Coarsely grate the marzipan. Stir with the whisk of the hand mixer until smooth, adding the egg white. Coarsely chop the almonds and ginger and mix into the marzipan.
Wash the peaches, cut them in half and remove the stone. Spread the marzipan mixture on the peach halves, place in an ovenproof dish. Drizzle syrup over it. Mix almond flakes and 25 g sugar, sprinkle over the peaches.
Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for about 20 minutes. Stir the sauce once again. Serve peaches with the sauce.