Step 1

Place the egg whites with the granulated sugar in a container and heat them in a double boiler over a saucepan containing a little water.

Step 2

Mix with a whisk and check the temperature with a candy thermometer, which should read at least 131°F / 55°C (the sugar should be completely dissolved).

Step 3

Pour the mixture into the bowl of a mixer fitted with the whisk attachment and beat at high speed for about 15-20 minutes until the meringue is white and has firm peaks. (Meringue should be completely cool)

Step 4

Lower the speed of the mixer and add the butter piece by piece, then resume high speed and mix for at least 5 minutes. (the mixture can go from liquid to grainy, so keep beating until you have a thick, smooth cream)

Step 5

Add vanilla, salt and melted white chocolate and mix again for 2-3 minutes.

Step 6

Change the whisk to a flat spatula and mix again for 2 minutes at slow speed to loosen the buttercream and remove the excess air that has been incorporated to make a smoother cream.