Place the egg whites and sugar in a heat proof bowl. We prefer to use the metal bowl of our stand mixer.

Fill a pot smaller than your bowl with a couple inches of water and bring to a boil. Once boiling turn down to a simmer and set the bowl on the pot to create a double boiler. Continuously stir the egg whites and sugar until the sugar has fully dissolved or the temperature reaches 160 degrees on a candy thermometer.

Transfer the bowl to a stand mixer fitter with the whisk attachment and mix on high until the mixture holds stiff peaks, about 8-10 minutes.

While the meringue is mixing cut the butter into 1 inch cubes. If you have not already melted your chocolate you will need to do so at this time.

When the meringue forms stiff peaks continue mixing on high and add the butter one cube at a time. Once all the butter has been added, mix in all the vanilla. After the vanilla has been added continue mixing on high for 5 minutes to create your silky smooth buttercream.

Mix in the melted chocolate on low-medium speed untill fully incorporated.