French Buttercream Frosting

Instructions

• Remove butter from the refrigerator and cut into tablespoon-sized pieces. Leaving the butter out while you work on the next few steps gives it just the right amount of time to soften slightly (touching it will leave a tiny indentation) while still ensuring that it is quite cold.
• Place sugar and water in a small heavy-bottomed pot on low heat. Whisk to dissolve the sugar.
• Once sugar is dissolved, raise heat to medium-high and stop whisking. Heat until sugar syrup reaches 240 F according to a candy thermometer (soft ball stage). Once the temperature gets above 210 F, monitor it closely; the temperature can increase very quickly.
• While the sugar syrup comes to temperature, in a stand mixer fitted with the whisk attachment, whisk egg yolks and salt until frothy (about five minutes on high speed). Once the sugar syrup is ready, turn the mixer on low speed and very slowly drizzle the hot syrup into the center of the bowl. Be very careful during this stage as there are three potential things that could go wrong. If the mixer is on too high, the syrup could splatter and burn you. If the syrup hits the sides of the bowl, it will stick and crystallize immediately. If you pour in the syrup too quickly, it can cook the eggs. Pour the syrup slowly and steadily into the center and you’ll be fine.
• Whisk on high speed for ten minutes or until the bowl cools to room temperature. If the bowl feels at all warm, keep whisking.
• Switch to the paddle attachment and, on medium speed, beat in the butter one tablespoon at a time.
• Turn the mixer up to high speed and keep beating until the frosting is light and fluffy. During this process, the frosting may look soupy or curdled. Just keep mixing and eventually it will come together again and become beautiful frosting (this can take up to ten minutes).
• Mix in vanilla.