Soak gelatine in 140g cold water
Boil and reduce sugar and water to (hardball stage, 127c)
Meanwhile whip egg whites to hard peak in the kitchen aid and leave
When syrup has reached 127c slide the gelatine and water its soaked in and whisk well
Now start the kitchen aid again and slowly pour in the syrup in to the whites, add vanilla and whisk for 10 minutes until stiff and glossy
Meanwhile oil a shallow small tray and dust well with cornflour then icing sugar all over
Now add the meringue and spread flat with a glove on your hands or a wet palette knife, (this will be hard to do)
Now cling film the top and put in the fridge for 3 hours to set
Dust a work surface with cornflour then icing sugar well, then remove marshmallow from fridge and turn out onto the bench, dust a sharp knife with cornflour and cut to desired shape
Leave on a wire rack spread out at room temperature for 30 minutes to dry a little
Store in airtight container for up to 5 days at room temperature