Boil sugar, glucose, and water in a heavy pan until the mixture reaches 127°C.
Beat egg whites with an electric whisk until stiff peaks form.
Slide soaked gelatine and its water into the hot syrup and transfer to a metal jug.
Whisk syrup into egg whites with vanilla for 10 minutes until stiff and shiny.
Spoon half the mixture into a 30cm x 20cm tray dusted with sugar and cornflour.
Lay sugar-coated raspberries over the mixture and cover with the remaining marshmallow.
Set for one hour, then turn out onto a dusted surface and cut into squares.
Serve as they are or with melted white chocolate for dipping.