Sift the flour and cornflour. Add about one third of the sugar and sift twice.
Beat the egg whites until foaming.
Add the cream of tartar and salt and continue beating until the whites become stiff.
Whisk the remaining sugar into the egg white, 15 ml at a time.
Continue whisking for 60 seconds until the mixture is glossy and forms stiff peaks.
Beat in the vanilla.
Fold in the flour in three batches.
Spoon the batter into a chiffon tin which has not been greased.
Bake at 175 ºC for 40-45 minutes or until the cake is done.
Leave the cake to cool upside down in the tin so that it does not collapse.
Place all the ingredients in a large glass bowl and beat by hand for 1 minute. Place bowl over a pot of boiling water and beat with an electric beater for 6 minutes, until stiff peaks form.
Remove from the heat and continue beating until thick enough to spread.
Coat the cake with frosting and leave to set.
Decorate with frosted rose petals.