To many home cooks, buttercream cake icing is butter whipped with confectioners’ sugar and flavoring. To pastry chefs, buttercream usually means butter whipped with meringue or beaten egg yolks. There are three basic types of egg-based buttercreams, all of which are lighter and more luxurious than the often gritty and overly sweet confectioners’ sugar version.
Swiss buttercream starts with Swiss meringue: Egg whites and sugar are heated together in a mixing bowl over a hot-water bath until the sugar dissolves, then they’re whipped to stiff peaks. Next, butter and flavorings are whipped in. Swiss buttercream is quick and easy to make, but it’s denser and less stable than Italian buttercream.
The lightest and sweetest of the buttercreams, Italian buttercream, is based on Italian meringue, made by whipping soft-ball-stage (234° to 240°F) sugar syrup into already-whipped egg whites, effectively cooking and stabilizing the whites. Once the meringue cools a bit, soft butter and flavorings are whipped in. Our buttercream recipeis a simplified version of Italian buttercream that uses corn syrup in the sugar syrup, so it’s not necessary to monitor the syrup temperature with a thermometer.
Decadent French buttercream uses the same technique as Italian buttercream except that it begins with beating the sugar syrup into whipped whole eggs or whole eggs plus extra yolks, rather than using just egg whites. In addition to giving it a yellow hue, the yolks make French buttercream richer and heavier, in contrast to the billowy texture and snowy white color of Italian buttercream.