Brown Sugar Swiss Meringue Buttercream

Silky smooth brown sugar Swiss meringue buttercream is the perfect topper for your cupcakes or cake! It has a rich, not-too-sweet taste, pipes beautifully, and pairs with so many flavors.

Recipe includes a how-to video!

Course Frosting

Cuisine American

Prep Time 35

Cook Time 10

Total Time 45

Servings servings (see note)

Calories 167kcal

Author Sam Merritt

Equipment

Stand mixer with a metal bowl and whisk and paddle attachment.
Medium saucepan
Instant-read thermometer (optional but recommended).

Ingredients

6 large egg whites (210g / 7.5oz / 210ml)
1 ¾ cups (350 g) brown sugar firmly packed (I use and recommend a blend of light and dark brown sugar, but you may use just light 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

Instructions

In the clean, dry bowl of a stand mixer, combine egg whites, brown sugar, and salt and whisk until well-combined. Set aside.
6 large egg whites, 1 ¾ cups (350 g) brown sugar, ½ teaspoon table salt
Fill a medium-sized saucepan with about 1 ½” (4cm) water and bring to a simmer over medium-low heat.
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.
Carefully remove the bowl from the water, dry off the bottom, and attach it to your stand mixer fitted with the whisk attachment.
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).
Allow the meringue to cool completely before proceeding. The bowl shouldn’t feel warm at all (feel near the base).
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.
1 ½ cups unsalted butter
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.
Add vanilla extract and stir until combined. Use frosting immediately.
1 teaspoon vanilla extract

Video

Notes

Servings/Yield

This recipe yields approximately 5 cups of frosting. I find this is enough to frost a single layer 9x13 cake or a 2-layer 8” or 9” cake or modestly frost 24 cupcakes or very generously frost 12 cupcakes (you’ll likely have a little left over).

Stand mixer

I really recommend using a stand mixer for this recipe. While you can substitute a double boiler and an electric hand mixer, it is going to take quite a long time and a lot of effort to whip the meringue with an electric mixer (and I’d even be worried about burning out the motor).

Egg whites

Egg whites can be warm or cold, it doesn’t matter. Fresh eggs are more reliable than store-bought, but store-bought egg whites should work so long as there are no additives.

Butter

If using salted butter, omit the salt called for in the recipe. The butter should not be oily/greasy or it’s too warm and the buttercream will curdle. Conversely, it shouldn’t be too cold or the frosting won’t whip smoothly. I aim for a butter around 69-70F (20C) (I use an instant read thermometer to check the temperature).

Troubleshooting

Please see the post for detailed troubleshooting instructions.

Storing

I recommend using this frosting immediately after preparing it, but it can be stored. Place in a container with a piece of plastic wrap or parchment directly against the surface and then seal the container. Place in the refrigerator for up to a week. When ready to use, allow it to come completely back to room temperature (in the container) and then re-whip using the paddle attachment before using. If it looks curdled or separated, continuing to mix should bring it back together. Freezing this frosting can be a pain to use afterwards so I don’t really recommend it.

Once used to frost a cake/cupcakes it will keep for at least 2 days at room temperature, 5 days in the refrigerator, or a month in the freezer.

Nutrition