Swiss Meringue Buttercream

In a large HEAT-PROOF mixing bowl (preferably the metal bowl of a standing mixer), add the egg whites and 2 cups of sugar.

Select a saucepan that the heat proof mixing bowl can set on top of, but not fall into. Fill this saucepan with several inches of water and bring to a low boil.

Place the mixing bowl with egg whites and sugar over the boiling water (similar to a double boiler set-up). Whisk the egg whites while heating until the sugar is completely dissolved - the egg whites will be warm to the touch and if you rub a bit of the egg whites between your fingers, it will be smooth. You should not feel any sugar granules. Remove from heat.

Attach mixing bowl to the standing mixer. With the WHISK attachment, beat egg white mixture on HIGH speed for 10-12 minutes. The egg whites will cool and beat into a glossy meringue with stiff peaks. Feel the bottom of the mixing bowl to ensure it is cool to the touch before proceeding on.

When the meringue has formed stiff peaks and is cooled, add the butter - 1-2 cubes at a time. Mix each addition in to the meringue completely (still using the WHISK attachment) until incorporated.

Continue adding 1-2 cubes of butter at a time until it is all combined.

Scrape down the sides of the bowl and switch out the whisk for the PADDLE attachment. Add vanilla extract and a pinch of salt.

Beat on the LOWEST speed using the PADDLE attachment for 4-5 minutes or until the airy mixture becomes smooth and thick like a gorgeous frosting. (see notes below for troubleshooting consistency issues).

To frost cupcakes with a swirl, fit a large piping bag with cake decorating tip #1M. Fill the piping bag with buttercream. Pipe buttercream onto cupcakes in a counter-clockwise direction, swirling up and toward the center.