Quick Swiss Meringue Buttercream (Pasteurized Egg Whites and Microwave version)




This recipe is a streamlined take on my Swiss Meringue Buttercream. It’s one of my favorites because it delivers the same smooth texture and balanced flavor—just faster. Instead of whipping a traditional meringue, we dissolve sugar directly into pasteurized egg whites. To dissolve such a high ratio of sugar, we need to use heat. You can use a bain marie but I often use the microwave as it’s quicker and just as effective. The result is a rich, silky buttercream that rivals the classic method in both taste and performance.
To learn more about the basics of Swiss Meringue Buttercream, check out my complete guide.
I also have a pretty comprehensive video on Swiss Meringue Buttercream:
Step by step:
Coming soon!
Video
Read this before you begin
Measure by weight, if possible.
Measuring by weight is the best way for you to replicate my recipes. I develop recipes using ingredients (even liquids) measured in grams, which is why you see them listed first in the recipe cards. For measurements under 5 grams, I will typically only list the volumetric measurements (teaspoons, etc.), as most home scales are not precise for such small weights.
In most cases, I have converted grams to volumetric measurements (aka US customary units) for bakers who prefer this method. However, the measurements are not as precise and may have awkward proportions. The recipes should still work, but for the ultimate precision, try to use weight.
This is the OXO scale I use daily. I also purchased this budget version of a good scale, which I keep at my Mom’s house for baking. If you’re interested in other tools I use for my baking, I’ve compiled a list here.
Use room temperature ingredients.
All my ingredients should be used at room temperature, or 65-75 °F/18-24 °C. I will always indicate if you need something outside this range. If no details are given, room temperature is the default.
Pay attention to the ingredient descriptions.
I try not to be brand-specific, but I will always note an interesting result from a type of ingredient, be it negative or positive.
A specific note regarding salt: I use Diamond Crystal Kosher salt for everything on this site except for frostings. In frostings, you want the salt to dissolve more easily, and kosher salt tends to leave granules behind. If you substitute table salt (more finely granulated) for recipes that list kosher salt, you must use half the volume indicated in my recipes.
Substitutions are hard.
That said, substitutions aren’t impossible but can be the toughest part of recipe development. Small swaps, like reduced-fat milk (2% fat) for whole milk (3.5% fat), usually work fine. However, bigger changes—such as replacing oil with applesauce or sour cream with Greek yogurt—can significantly impact texture and density.
Be wary of general, all-purpose substitutions in baking; I find that usually there is never a one size-fits-all solution. I carefully select ingredients for my recipes, so for the best results, start with the original recipe and modify with caution.
Read all the recipe instructions before beginning.
I’m in the “Pre-read the Chapter before Class Lecture” club... and I invite you to join! Baking new recipes can be intimidating, so let’s set you up for success. I want you to think about timeframes. Most fillings and frostings can be made ahead of time, and give you an extra day for mental space. Also, as you become a more proficient baker, you can anticipate and recognize steps. (“Oh, this has a meringue step, so I’ll need an extra clean bowl…” etc.) Ensure you go down the ingredient list and have everything at the right temperature.
Quick Vanilla Swiss Meringue Buttercream (Pasteurized Egg Whites version)




- 40 g (2 tablespoons + 2 teaspoons) pasteurized (carton) egg whites*
- 67 g (⅓ cup) white granulated sugar**
- 85 g (6 tablespoons) unsalted butter
- 7 g (1 tablespoon) powdered sugar***, sifted if clumpy
- ½ + ⅛ teaspoon vanilla extract
- small pinch of fine salt
- 40 g (2 tablespoons + 2 teaspoons) pasteurized (carton) egg whites*
- 67 g (⅓ cup) white granulated sugar**
- 85 g (6 tablespoons) unsalted butter
- 7 g (1 tablespoon) powdered sugar***, sifted if clumpy
- ½ + ⅛ teaspoon vanilla extract
- small pinch of fine salt
- 121 g (½ cup) pasteurized (carton) egg whites*
- 200 g (1 cup) white granulated sugar**
- 254 g (1 ⅛ cups) unsalted butter
- 23 g (3 tablespoons) powdered sugar***, sifted if clumpy
- 2 teaspoons vanilla extract
- ⅛ teaspoon fine salt
- Make the meringue syrup.
Add pasteurized (carton) egg whites and sugar to a microwave-safe bowl or measuring cup. Stir until sugar is completely mixed in and hydrated.
Microwave on high power (1200 watts) using 20 second intervals. Remove the bowl between every heating, give it a stir and feel with your fingers (be careful if it’s hot!) if there are any sugar granules. Keep heating until the sugar is completely dissolved.
Allow to cool to room temperature before adding to the butter in the next step. If I’m moving through this recipe non-stop, I’ll place the bowl of meringue syrup in a bowl of ice water to cool it more quickly. - Prepare the Frosting Butter.
Add slightly softened butter to the stand mixer bowl and whisk on high for about 2 minutes, scraping down the sides once. The butter should become lighter in color and smoother and ball inside the whisk.
Add powdered sugar*** (see my notes below to assess how much to add), vanilla extract, and a pinch of salt, then whisk on medium-high for another 1-2 minutes. - Combine the meringue syrup with the Frosting Butter.
Add the room temperature syrup/meringue in 3–5 additions, mixing for 30 seconds each. Once fully incorporated, scrape the bowl and mix on high for 1 minute. - Flavor and smooth the frosting.
Switch to the paddle attachment and mix on low for a few minutes to remove air pockets. Taste and adjust vanilla or salt if needed. The frosting should be ultra-smooth and creamy.

Recipe Card - Adriana's Notes
*Liquid egg whites are sold in a carton. In the US, eggs that are removed from their shells must be pasteurized before sale. This process kills any bacteria in the egg products and ensures they are safe to consume straight from the container.
**You can use powdered sugar here, but ensure you use the weight measurement to get the necessary amount.
***You can vary the amount of powdered sugar. I’ve given a mid-range amount, creating a moderately sweet buttercream. You can double this amount to get a sweeter version. Some things to consider - emulsion buttercreams tend to get less sweet as they sit out (usually over 24 hours), so I usually err on the side of a tad sweet if I’m serving it the next day. Also, with these types of vanilla buttercreams, you can go only in one of two ways: sweet or buttery. In other words, if you tone down the sweetness, be prepared for a ~buttery~ buttercream. If this is what you like, you can omit powdered sugar entirely for a luxurious buttery version—just be sure to whip the butter thoroughly in Step 3 before adding the meringue to prevent a dense texture.