1: 2: 3: Swiss Meringue Buttercream
- Put sugar, salt and egg whites in the heatproof bowl, and set over a pan of simmering water. Whisk constantly until sugar is dissolved, and mixture registers 140F on an instant-read thermometer. If the sugar is not completely melted, your final product will be grainy.
- Transfer bowl to an electric mixer fitted with the whisk attachment. Beat on medium-high speed until fluffy and bowl is cool to the touch, about 10 minutes. Continue beating until stiff, glossy peaks form. Meringue will be white with a bright sheen AND very sticky.
- Reduce speed to medium-low; add butter a few cubes at a time, beating well after each addition. If the meringue is not cool enough it will completely melt the butter.
- Continue beating till all the butter is incorporated. At one point the mixture will look "broken" looking watery and separated like curdled milk. Continue mixing it will all come together I promise.
- Beat in vanilla or other flavorings or color paste. Buttercream can be refrigerated in an airtight container up to 3 days or frozen up to 1 month. Bring to room temperature before using; beat on lowest speed until smooth, about 3 minutes.