Vanilla Buttercream
150 grams of egg whites
300 grams of granulated sugar
450 grams of room temperature unsalted butter (if you can get white butter, so much the better)
1 Tbs vanilla extract
In the bowl of an electric mixer, whisk together egg whites and the sugar into soft peaks. Place over a water bath until sugar is dissolved and you can draw a figure 8 in it with your whisk. It will look like light marshmallow. Allow to cool to room temperature.
Bring bowl to the electric mixer and whip until stiff peaks form and the bottom of the bowl feels cool.
Then add butter, a tablespoon at a time while whipping. It might look like it is curdling at one point but continue to whip until it comes together.
Add vanilla extract and mix until incorporated. Refrigerate for at least an hour before piping.