Lightly score and cross on the base of each peach. Put the peaches into a large heatproof bowl and cover with boiling water. Set aside for 2–3 minutes.
Fill another bowl with iced water. Using a slotted spoon, transfer the peaches to the iced water to prevent further cooking. Once cool enough to handle, remove the skin with a paring knife, cut the peaches into quarters and remove the stone.
Melt the butter in a frying pan over a medium heat. Add the peaches and pan-fry until they start to colour. Add the sugar and pistachios and cook until the sugar has dissolved and the peaches and pistachios are golden and caramelised. Add a splash of masala to de-glaze the pan. Set aside to cool.
Put the egg yolks and masala in a heatproof bowl and whisk to combine Place the bowl over a pan of boiling water, making sure the bowl doesn’t touch the water, and whisk continuously until the mixture is creamy and has more than quadrupled in size.
To assemble, spoon a layer of zabaglione into dessert glasses and top with a spoonful of peaches. Repeat with the remaining zabaglione and peaches, top with the caramelised pistachios, sprinkle over the amaretti biscuits and serve.