Creamier and less gritty than its American counterpart, Swiss meringue buttercream frosting combines whipped egg whites with sugar, salt and vanilla. Because frosting recipes often yield enough for two cakes, you may be happy to know this buttery frosting stores well to top a second cake -- or a batch of cupcakes. Alternatively, make the Swiss meringue buttercream frosting ahead of time, so post-baking assembly comes together quickly.
To make buttercream frosting in advance, make it no more than a week before you plan to use it. Store it in an airtight container in the refrigerator. When you're ready to use it, let the frosting come to room temperature, then beat it on low or medium for about 15 minutes.
Storing Extra Portions
Extra Swiss meringue buttercream can go into the refrigerator if you plan to use it within seven days. Otherwise, freeze it in a storage bag or freezer container for up to four months. To use it, let the buttercream frosting come to room temperature, which may take two hours or more. Beat the frosting for 15 minutes on a low to medium setting. It may initially look like the frosting separated, but it returns to a smooth consistency with enough beating.