Brown Sugar Swiss Meringue Buttercream

Ingredients

• 6 large egg whites ((210g / 7.5oz / 210ml))
• 1 ¾ cups brown sugar
• ½ teaspoon table salt
• 1 ½ cups unsalted butter (softened nearly to room temperature and cut into Tablespoon-sized pieces (see note))
• 1 teaspoon vanilla extract

Steps

1. 1

   In the clean, dry bowl of a stand mixer, combine egg whites, brown sugar, and salt and whisk until well-combined. Set aside.

2. 2

   Fill a medium-sized saucepan with about 1 ½” (4cm) water and bring to a simmer over medium-low heat.

3. 3

   Place the mixer bowl over the simmering water, ensuring the bottom of the bowl doesn’t touch the water, and whisk constantly until the sugar dissolves and the mixture reaches 160F (70C). This will take some time (10 minutes would not be unusual), be patient. To check if the sugar is dissolved, you can carefully drizzle a small amount of the syrup onto a plate, let it cool slightly, then rub the mixture between your fingers – it should feel smooth and not gritty.

4. 4

   Carefully remove the bowl from the water, dry off the bottom, and attach it to your stand mixer fitted with the whisk attachment.

5. 5

   Beat the syrup on medium to medium-high speed until stiff peaks form (meringue will be thick, glossy, opaque and increased in volume and will hold its shape, meaning if you remove the whisk and flip it upside down the meringue will hold its peak and not fold over itself). This can also take some time, 10 minutes would not be unusual (or even longer).

6. 6

   Allow the meringue to cool completely before proceeding. The bowl shouldn’t feel warm at all (feel near the base).

7. 7

   Switch to your paddle attachment and set mixer to medium speed. Add butter, 1 Tablespoon at a time, not adding the next until the previous one has completely incorporated. If mixer looks curdled or starts to separate, don’t panic just keep mixing (making sure you’re giving your butter time to incorporate). If you’ve added all of your butter and are still having issues, please see the troubleshooting section in the post.

8. 8

   Once all butter is incorporated and mixture is smooth, scrape down the sides of the bowl, increase speed to medium-high and stir again until smooth and thick.

9. 9

   Add vanilla extract and stir until combined. Use frosting immediately.