A how-to-guide for making Swiss Meringue Buttercream! This frosting is great for piping/decorating and can be used under fondant. Yields enough frosting to cover 24 cupcakes or one 8" or 9” two layer cake, or one 9x13” cake. If this is your first time making Swiss Meringue Buttercream I recommend reading through the post or watching the video (below) before beginning.
Thoroughly clean and dry the bowl of a stand mixer. Make sure there is absolutely no grease or water on the inside of the bow (or on your whisk, or anything that will come in contact with your egg whites) or your egg whites will not whip properly.
In your (clean) mixer bowl, combine egg whites, sugar, and salt and whisk until combined.
Heat about 1 1/2 inches of water over medium-low heat in a medium-sized saucepan and bring to a simmer. Make sure that you are using a saucepan that your mixer bowl can fit in without touching the bottom of the pan or touching the water.
Rest the bowl of your mixer in the pot over the simmering water.
Whisk egg white/sugar/salt mixture constantly until the sugar is dissolved and mixture is no longer grainy (if you rub a small bit between your fingers it should feel smooth and not at all gritty) and the mixture reaches 160F (70C). This will take several minutes.
Remove mixing bowl from heat and dry the bottom of your bowl. Fit bowl into your stand mixer.
Using a whisk attachment, beat the egg whites on medium/medium-high speed until meringue is thick and glossy and you have achieved stiff peaks (see photo in post or see video below for visual). This will take about 10 minutes or so.
Once you have achieved stiff peaks, stop beating and allow bowl to cool down completely. The bowl must no longer be warm to the touch anywhere before proceeding or you will melt your butter and ruin your buttercream.
Once bowl is no longer warm to the touch (make sure you are feeling near the bottom of the bowl), switch out whisk attachment for paddle attachment. Turn mixer to medium speed and add butter one Tablespoon at a time. Don’t add the next tablespoon of butter until the previous one is incorporated into the meringue. If you notice that your buttercream starts to break down or look curdled, just keep mixing and it will come together. If it still doesn’t come together (it could take some time), place the mixer bowl in the fridge for about 10 minutes and then try mixing again.
Once all butter has been beaten into the meringue, scrape down the sides of the bowl and stir again. Beat on medium/high until smooth and thick.
Stir in vanilla extract or other flavoring and any food coloring, if using.
Spread or pipe over cupcakes or cake! I used an Ateco 848 for the cupcakes shown in this post.
¹I do not recommend using pasteurized egg whites (the kind that you buy from the store in a carton) for this recipe.²If using a liquid measuring cup, you would fill to directly between the ¾ and 1 cup line
Making in Advance/Storing
Swiss Meringue Buttercream may be made several days in advance of using it. Store refrigerated in an airtight container and then allow frosting to come to room temperature and stir well before using. If the buttercream seems to have lost some of its volume/lightness, use an electric mixer to whip it until it returns to its original texture.
Here are a few recipes to use up your leftover egg yolks!