To make the iced yoghurt, heat the sugar and water in a saucepan over a medium heat until it reaches 118 degrees C on a thermometer. Meanwhile, whisk the egg whites until soft peaks form. Once the sugar syrup reaches temperature, remove from the heat and slowly pour in a steady stream into the egg whites, whisking slowly. Turn the speed up to high and whisk until the bowl feels just gently warm to the touch.
Whisk the yoghurt in a large bowl to loosen it, then fold in the meringue. Whip 250ml cream to soft peaks then fold in until combined. Transfer to a 1 litre loaf tin or other freezeable container and freeze at least 5 hours or overnight.
To roast the peaches, preheat the oven to 160 degrees C. Arrange the peaches, cut side up, in a roasting dish, and drizzle over the honey and Amaretto. Sprinkle with the demerara sugar then roast for about 20 minutes, spooning the juices over the fruit every few minutes, until soft. Leave to cool completely then cut each half into four pieces.
Ten minutes before serving, take the iced yoghurt out the freezer to soften. Whip the remaining 150ml cream with the pistachio paste and honey.
Arrange a few peach slices in the bottom of six glasses or sundae dishes. Top each with a scoop of ice cream, a dollop of whipped cream, a sprinkle of honeycomb and pistachios. Repeat, finishing with a few larger pieces of honeycomb. Serve immediately.
Recipe by thelittleloaf at http://www.thelittleloaf.com/2014/05/26/iced-yoghurt-peach-pistachio-sundaes-with-honeycomb/