This is my go-to buttercream recipe. It takes some time, and lots of dishes, but it is worth it in the end if you ask me. The texture is perfectly smooth and light with no unpleasant grains of sugar remaining thanks to the fact that the sugar is dissolved in the egg whites. I like my frosting not to be too dense, or too sweet, and this is just that.
Swiss Meringue Buttercream
Credit: Martha Stewart's Wedding Cakes by Martha Stewart
5 large egg whites
1 cup plus 2 tablespoons sugar
Pinch of salt
1 pound (4 sticks) unsalted butter, cut into tablespoons, room temperature
1 ½ teaspoons pure vanilla extract
4.5 ounces semi-sweet chocolate, melted and cooled to room temperature (**if you are making chocolate buttercream)
- Combine egg whites, sugar, and salt in the heatproof bowl of a standing mixer set over a pan of simmering water. (I achieve better results with my double-boiler, and then move the mixture to the mixer bowl.) Whisk constantly by hand until mixture is warm to the touch and sugar has dissolved (the mixture should feel completely smooth when rubbed between your fingertips).
- Attach the bowl to the mixer fitted with the whisk attachment. Starting on low and gradually increasing to medium-high speed, whisk until stiff (but not dry) peaks form. Continue mixing until the mixture is fluffy and glossy, and completely cool (test by touching the bottom of the bowl), about 10 minutes.
- With mixer on medium-low speed, add the butter a few tablespoons at a time, mixing well after each addition. Once all butter has been added, whisk in vanilla. (If you would like to make chocolate buttercream, melt 4.5 ounces semi-sweet chocolate, and cool to room temperature. Fold the the cooled chocolate in at this point, along with the vanilla.) Switch to the paddle attachment, and continue beating on low speed until all air bubbles are eliminated, about 2 minutes. Scrape down sides of bowl with a flexible spatula, and continue beating until the frosting is completely smooth. Keep buttercream at room temperature if using the same day. Refrigerate if using later, but bring to room temperature and beat in mixer again with paddle attachment before using.