Grease and line a 20 x 30cm baking tin with baking paper.
Finely chop the pistachios in a food processor and set aside. Mix the icing sugar and cornflour together in a small bowl. Dust the icing sugar mix over baking paper in an even layer and tip the excess back into the bowl.
Soak the gelatine leaves in a bowl of cold water for 10 minutes until soft and, meanwhile, prepare the remaining ingredients. Place the egg whites in the bowl of a freestanding mixer fitted with a whisk attachment, and add the salt and 15ml of the castor sugar.
The remaining castor sugar and glucose into a medium-sized saucepan and add 150ml water. Place over a medium heat and stir gently to dissolve the sugar. Increase the heat and bring the mixture to the boil. Continue to cook at a steady boil until the syrup reaches a temperature of 120°C or 248°F on a sugar thermometer. Slide the pan off the heat.
Drain the gelatine from the water and blot dry on a clean tea towel. Quickly whisk the egg whites until stiff peaks form. Still working quickly, add the gelatine to the hot syrup and stir until completely combined. With the mixer on medium speed, add the hot syrup to the whisked egg whites in a slow and steady stream. Avoid pouring the syrup directly onto the whisk as this will cause it to splatter onto the sides of the bowl instead of into the mixture. Continue to whisk for a further 4 minutes until the marshmallow is cool, very glossy white and stiff enough to hold a firm ribbon trail when the whisk is lifted from the bowl. Add the rosewater and mix to combine.
Using a toothpick, add a tiny amount of pink food-colouring paste and whisk until the marshmallow is evenly coloured. Add more food colouring in small increments to reach your desired shade of pink – a little goes a long way.
Scoop the marshmallow into the prepared tin and spread level with an offset palette knife. Scatter with the pistachios and leave in a cool place for at least 2 hours until set. Cover with clingfilm and leave for a further 4 hours or overnight.
Sift the reserved icing sugar mix on to a large tray that you have lined with baking paper. Carefully turn out the marshmallow on to it and peel off the lining paper. Using a greased kitchen knife, cut the marshmallow into delicate fingers, then roll the sides and bottom of each piece in the icing sugar mix.
The marshmallows will keep for up to one week in an airtight box.
Image and text: Ideas
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