Martha Stewart's Swiss Meringue Buttercream
- 1 1/2 cups Sugar
- 6 large Egg Whites
- 4 sticks Unsalted Butter (room temperature; cut into pieces)
- 1 teaspoon pure Vanilla Extract
- Whisk together sugar and egg whites in a heatproof mixing bowl set over (not in a pan of simmering water. Whisk until warm and sugar is dissolved (mixture should feel completely smooth when rubbed between your fingers), 2 to 3 minutes. Remove from heat.
- With an electric mixer on medium speed, whisk egg-white mixture 5 minutes. Increase speed to medium-high, and whisk until stiff, glossy peaks form and meringue has cooled (test by feeling bottom of bowl), about 6 minutes.
- Reduce speed to medium. Add butter, 1 piece at a time, beating well after each addition. Beat in vanilla. Buttercream can be refrigerated up to 3 days or frozen up to 3 months in an airtight container. Bring to room temperature and beat on low speed until smooth before using.