Preheat the oven to 200°C.
Grease and line a roasting tray with nonstick baking paper. Combine the caster sugar, vanilla pod and water in a saucepan and heat over a medium heat, swirling the pan, to help dissolve the sugar. Once dissolved, continue to cook the sugar syrup for 5 minutes. Remove from the heat and set to one side.
Crush the amaretti biscuits in a mixing bowl, then fold the mascarpone into the mixture to make the stuffing. Spoon into the peach halves and stud with the blanched whole almonds. Drizzle with some of the vanilla syrup then roast in the oven for 15 minutes until the stuffing if golden brown and the peaches are soft.
Remove and allow to cool a little before arranging on serving plates. Drizzle with some of the remaining vanilla syrup before serving.