Swiss Meringue Buttercream Frosting

This is my go-to frosting - it's silky, light, fluffy, and not too rich because of the slightly lower ratio of butter to meringue. Many people use 3/4 - 1 stick of butter per 1 egg white; I prefer using a little over 1/2 stick of butter per egg white, which keeps the frosting light but still able to hold its shape when piped.

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Swiss Meringue Buttercream Frosting
(makes about 7 cups of frosting – enough for a 3-layer 9” cake)

7 egg whites
1 ¾ cups granulated sugar

3 ½ sticks (14 oz) unsalted butter, cut into tablespoons and at room temperature
1 teaspoon vanilla extract

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Put the egg whites and sugar in the bowl of a standing mixer. Set the bowl over simmering water (the bottom of the bowl should not touch the water) and whisk the mixture until it reaches 140 F. If you don’t have a thermometer, don’t worry – the mixture will turn thick and white and all the sugar should be dissolved – this should take about 5 minutes.

Transfer the bowl to the mixer and, with the whip attachment, mix on high speed (8) until the whites are fluffy and cool, 10-12 minutes.

Once the mixture is cool, scrape down the sides of the bowl with a spatula.  Add the butter a few pieces at a time, mixing well before adding more and scraping down the sides of the bowl occasionally. The mixture will start to look curdled after you have added about 3 sticks of butter. Don’t worry – just add the rest of the butter and keep mixing until it comes together and is smooth.  Add the vanilla extract and mix for another 15 seconds until fully incorporated.

Scrape down the sides of the bowl with a spatula.  Replace the whisk with the paddle attachment and beat on low speed (2) for 5-7 minutes – this gets rid of air bubbles, thereby making the frosting smoother and more even when you apply it to the cake.

[You can store the frosting in the fridge for 3-4 days or in the freezer for 2-3 weeks. When you are ready to use the frosting, let it come to room temperature, then whip it on medium-high speed until it becomes light and fluffy and then beat with the paddle on low speed to remove air bubbles.]