Turn the oven down to 140C/fan 120C/gas 1. Mix 60g of the icing sugar with the flour. Whisk the egg whites until they reach soft peaks, then whisk in the caster sugar a spoon at a time, continually whisking, until the mixture is glossy and holds stiff peaks. Fold in the icing sugar mixture and spoon the meringue into a piping bag with a plain 1cm nozzle. Pipe little meringues of varying sizes onto a lined baking tray and cook for 1 hour, or until the meringues are hard. Open the door a couple of times to let out any moisture, or leave a wooden spoon in the door to leave it open a fraction. Leave to cool.