Italian Meringue Buttercream

Egg white-based buttercream, made by beating butter into Italian meringue, is made in almost the exact same way as egg yolk-based buttercream, except that soft ball-stage sugar syrup is poured into beaten egg whites instead of beaten egg yolks. Most professional chefs prefer buttercream made with egg yolks—probably because of its rich unctuousness—but when a perfectly white buttercream is called for, as on a wedding cake, the pale yellow egg yolk-based buttercream won’t work. You can make t