Seven-Minute Frosting

• 2 egg whites
• 350 g / 12 oz caster sugar

Whisk the egg whites with the sugar, cream of tartar and hot water in a large mixing bowl set over a pan of simmering water. This usually takes about seven minutes, hence the icing’s name. The frosting is ready when the meringue is thick enough to stand up in peaks. Remove the bowl from the heat, stand it on a folded cloth and continue whisking until the mixture is cool. Whisk in the vanilla es