The filling (except the peach flesh) can be prepared a few hours ahead and chilled.
Preheat the oven to 200C/gas 6/fan 180C. Halve and stone the peaches, then dig out a little flesh from the centre of each half, using a sharp-edged soup spoon. Put flesh and peaches to one side.
Tip the amaretti, almonds and chocolate into a food processor and pulse until the mixture is like coarse gravel. Add the spooned-out peach flesh, egg and honey and whizz for just a second or two to combine – don't over-process.
Spoon the stuffing into the peach halves, mounding it up a little. Arrange the peaches in a single layer in a heavy baking tin, then bake for 25-30 minutes or until the flesh is tender and the stuffing nicely browned. Serve hot, with a dollop of mascarpone or crème fraîche and a dusting of sifted cocoa powder.