Swiss Meringue Buttercream

• In the bowl of an electric stand mixer, add the egg whites and granulated sugar.  Whisk them together briefly by hand until just combined (so that the egg whites don’t scramble).
• Fill a sauce pan with a few inches of water and bring it to a simmer.  Place the mixer bowl with the egg white mixture on top to create a double-boiler. The water should be kept at a simmer and should not touch the bottom of the bowl.  This will indirectly being the eggs to a safe temperature without them becoming hard-cooked or scrambled.
• Occasionally stirring, heat the egg white mixture until it reaches 160°F on a candy thermometer.  The mixture will be very hot to the touch and the sugar should be dissolved.
•  Once the egg white mixture is hot, carefully return the bowl to the stand mixer.  Fitted with the whisk attachment, beat the mixture on high speed for 8 to 10 minutes.  When done, the meringue should hold shiny, medium-stiff peaks and the outside of the bowl will have returned to room temperature.
• With the mixer on medium-low, add in the butter - a couple tablespoons at a time.
• Once the butter has been mixed in, add the vanilla extract.
• Stop the mixer and swap out the whisk for the paddle attachment. Turn the mixer up to medium-high speed and mix until smooth and spreadable, 3 to 5 minutes (see Baker’s Notes for troubleshooting).
• For frosting a smooth cake, you will want to eliminate the air bubbles that were whipped into the buttercream during the process. Mix on low speed for a few minutes for the silkiest, smoothest buttercream.