Italian Meringue Buttercream is by far my favorite cake frosting. It has the perfect balance of rich flavor from the butter and lightness from the meringue. It’s not overly sweet, and it can be flavored with an endless variety of add-ins. It’s strong enough to pipe buttercream roses and stays soft at room temperature so it melts in your mouth.
Italian meringue buttercream requires egg whites, sugar, and butter. I tend to have quite a few egg whites in the fridge, mostly because my youngest son loves Pasta alla Carbonara – which calls for 5 egg yolks. If you don’t have egg whites, and you are concerned that you would find yourself with leftover egg yolks, I suggest you buy Pete and Gerry’s Organic Egg Whites. Not all egg whites sold in the store can be whipped, but Pete and Gerry’s can.
Because Italian Meringue Buttercream requires some time, I usually make a few unflavored batches and freeze them. It can stay frozen in bags or containers for up to three months. When I need it, I thaw it in the fridge the day before and then I bring it to room temperature on the day I need it. I add flavors and other ingredients when I revive/whip the buttercream, before using it. Sometimes, if the buttercream is too cold, it may curdle. Do not panic, just warm it slightly and whip it again. It will magically come back to life.
This recipe comes for a baking class I took at King Arthur Flour in Norwich, VT. I give Chef Jeff Hamelman full credit for its success. This recipe makes 4 to 4.5 cups of buttercream, enough to frost a two layer 8″ or 9″ cake. Be mindful that you will use sugar twice; first in the syrup and then in the egg whites, so there are two different quantities in the ingredient list, and sugar is mentioned twice in the directions. You also need a digital candy thermometer for this recipe.