Typically an Italian Meringue Buttercream die-hard fan, I quickly became a believer after I made this Stout Cake. Swiss Meringue Buttercream is much easier to make, and will dispel any worries about egg whites not being cooked ‘enough’.

Whether Swiss or Italian, meringue buttercreams should definitely be your go-to option for the simple reason that there is much less sugar compared to a traditional ‘American’ buttercream where the ingredients are just butter and icing sugar. That is, of course, unless you are opposed to having eggs in the first place. Both require the exact ingredients: egg whites, sugar, butter, and flavoring. Both involve melting the sugar to a syrup, making a meringue, then adding butter a little at a time. The only difference is how heat is introduced to the recipe.

The difference between Swiss and Italian meringue buttercream

To make Italian meringue buttercream, IMBC, it is the sugar that is cooked on a saucepan until it reaches 115C or 240F. Yes, hotter than boiling water, we are in biological weapon territory here! And then this sugar syrup will be drizzled on to a beating, yes, beating stand mixer, which already has the egg whites whipped to a soft peak stage. While it sounds terrifying, IMBC produces a silky smooth buttercream that is stable for even outdoor birthdays in the peak of summer. Speaking from experience, of course.
Swiss meringue buttercream, SMBC, on the other hand, isn’t as frightening to make. Here, the egg whites and sugar are cooked on a bain marie or a double boiler until it reaches the minimum safe temperature to consume eggs, which is 71C or 160F, which also is enough heat to melt the sugar granules. Then this ‘cooked’ mixture is transferred to a stand mixer to whip into a meringue, after which butter is added. SMBC produces a smooth, creamy frosting that holds up well for layering cakes as well as piping on cupcakes. It is also less intimidating to make.

It does, however, come with some challenges, but they are all temperature related. If you see it breaking or not coming together, you can refrigerate it for a while. If you see it too thick and buttery, you can warm it on a double boiler for a bit, although the latter is so much more rare than the former. Having a thermometer is essential in getting it right. I absolutely love my infrared thermometer, but a candy thermometer will work well enough.

Essentially, a buttercream is mainly butter, so please get a good one. Definitely unsalted, but not necessarily cultured. And then we have the eggs … fresh is best, but I have been known to use egg whites that have sat in the fridge for 2-3 days after I used the yolks to make ice cream, and it is all good. After your buttercream is done, it’s all about the flavor. Vanilla is always a crowd-pleaser, and you could and should pair it with your cake or cupcake: a shot of espresso, a few drops of lemon (or other essential) oil, or a 1/4 cup of chocolate ganache will definitely add so much, and distract from the ‘buttery’ taste. For the Stout Cake, I added a few tablespoons of Whisky Salted Caramel. It was sublime!