Instructions

• Combine 1 ½ cups granulated sugar and ½ cup water in a small saucepan. Stir over medium-low heat until the sugar dissolves, then bring to a steady boil. Cook without letting it darken further until the syrup reaches 240°F (soft-ball stage) on a candy thermometer. Be careful—the syrup is very hot.
• While the syrup heats, place 8 large egg yolks in the bowl of a stand mixer fitted with the whisk attachment. Whip on medium-high until the yolks are thick, pale, and foamy.
• When the syrup reaches 240°F, remove the pan from the heat. With the mixer running on low, very slowly and carefully drizzle the hot sugar syrup into the whisked yolks in a thin, steady stream (aim for the center). Do not pour too fast to avoid cooking or splattering.
• After all the syrup is incorporated, increase the mixer speed to medium and whip the yolk-syrup mixture until the outside of the bowl feels cool to the touch.
• Add 1 ½ cups room-temperature unsalted butter one tablespoon at a time, waiting for each tablespoon to be fully absorbed before adding the next. If the mixture looks separated at any point, continue whipping on medium until it comes back together before adding more butter.
• Add 2 teaspoons vanilla extract (or vanilla bean paste) and 1 pinch salt. Whip on medium until the buttercream is smooth, glossy, and fully combined.
• Use immediately or refrigerate briefly if needed; re-whip briefly on medium if chilled before use.