Giant chocolate marshmallows

1. Line a 900g loaf tin with parchment paper. Put the sugar, glucose and 150ml warm water in a pan. Dissolve the sugar over a low heat; brush the sides of the pan with water to stop it crystallising. Leave the syrup to simmer until it reaches 125˚C (hard ball stage) on a sugar thermometer; don’t stir. If you don’t have a thermometer, spoon a little syrup into a glass of cold water; if it sets immediately, then it’s at the correct temperature.

2. Meanwhile, melt the chocolate in a bowl set over a pan of barely simmering water; set aside to cool briefly. Separate the gelatine leaves and leave to soak in cold water for 5 minutes.

3. Just before the sugar syrup comes to temperature, use electric beaters or a freestanding mixer to whisk the egg whites and salt to stiff peaks in a large bowl. Put a tea towel under the bowl to secure it, then quickly and carefully pour the hot syrup down the inside of the bowl, whisking continuously. One at a time, squeeze the excess water from the gelatine leaves, then beat into the hot meringue. Keep beating until completelycool; about 10 minutes. Beat in the vanillauntil combined, then gently stir through the melted chocolate with a spatula until just rippled. Pour into the loaf tin and leave to set for at least 3 hours.

4. Sift the icing sugar, cornflour and cocoa powder onto a clean baking tray. Tip in the marshmallow; remove the parchment and coat with the sugar mixture. Cut the marshmallow into 12 large, even pieces and dust again. They will keep for up to 3 days, stored in an airtight container.