Using white vinegar, wipe your dishes, bowls, spatulas, whisk attachment, and any other tools that will be in contact with the meringue.
Separate the egg whites from the yolks. Measure the butter, and put it outside the fridge.
Start a double boiler with simmering water. Pour the egg whites and the sugar into the bowl of the stand mixer and place on the double boiler. Stir constantly until the mixture reaches 63°C/ 145°F
200 grams Egg white, about 6 eggs, 400 grams Granulated sugar
Transfer the bowl back to the stand mixer, and whisk until stiff peaks form,
Stop the mixer and let the meringue cool down. This will take from 5 to 10 minutes.
Once the bowl is not warm to touch, start whisking the meringue again and add the butter in chunks.
400 grams Butter
Meringue starts to deflate and curdle. Keep beating until all the butter is incorporated into the buttercream.
Add the vanilla extract, and switch to the paddle attachment. Beat the buttercream for a few minutes to remove some of the air incorporated into the cream.
2 teaspoon Clear vanilla extract