- Cook time: 35min
- Difficulty: medium
- Serves: 8
Put the granulated sugar, glucose and 200ml (7 fl oz) water in a heavy-based saucepan. Bring to the boil and continue cooking until it reaches 127C / 260F on a sugar thermometer.
Meanwhile, soak the gelatine in 140ml (1/4 pt) cold water. Beat the egg whites until stiff. When the syrup is up to temperature, carefully place the softened gelatine sheets and their soaking water into the sugar. The syrup will bubble up so keep and eye on it. Pour the syrup into a metal jug.
Continue to beat the egg whites – preferably with an electric whisk – while pouring in the hot syrup from the jug. The mixture will become shiny and start to thicken. Add the vanilla extract and continue whisking for about five to ten minutes, until the mixture is stiff and thick enough to hold its shape on the whisk.
Lightly oil a shallow baking tray, about 30 x 20cm (12 x 8in). dust it with sieved icing sugar and cornflour, then spoon the mixture over and smooth it ette knife if necessary.
Leave for at least an hour to set. Dust the work surface with more icing sugar and cornflour. Loosen the marshmallow around the sides of the tray with a palette knife, then turn it out on to the dusted surface. Cut into squares and roll in the sugar and cornflour. Leave to dry a little before packing them into an airtight box.