The Swiss Meringue Buttercream I Can’t Stop Making
This is the Swiss Meringue Buttercream recipe you’ll actually trust — even on warm and humid days. It’s light, silky, and not too sweet like traditional American buttercream frosting, and it’s surprisingly easy to make even if you’ve struggled with meringue in the past. Made with just five ingredients, this version uses a simple stability trick that helps it hold its shape beautifully — I even tested it outside in 89°F Florida heat, and it stayed smooth and picture-perfect an hour later. Whether you’re frosting a cake or piping cupcakes, this is the go-to recipe that delivers elegance, ease, and staying power.
Over the years, I’ve gotten so many requests for a frosting that isn’t super sweet and can hold up in the heat- and that’s exactly why I’m bringing you this Classic Swiss Meringue Buttercream recipe (aka SMBC).
It’s totally different from your classic American buttercream frosting, which is just butter, powdered sugar, and flavoring—and honestly, can be too sweet sometimes.
SMBC is made by heating and whipping egg whites and sugar into a glossy meringue, then beating in butter until it’s light, airy, and super smooth. It uses about half the sugar (and no powdered sugar!), so the flavor is way more balanced without losing any of the deliciousness. It holds up well outside on a hot day too!
It’s perfect swirled high over these white chocolate cupcakes or classic vanilla cupcakes. You can also slather it rustic style over a chocolate cake, or spoon it over this easy banana cake– you truly can’t go wrong.
As a trained pastry chef and Le Cordon Bleu grad, I want to break down exactly how to make this frosting. I know it can feel a little intimidating at first (heating egg whites?! a thermometer?!), and maybe you’ve heard it’s complicated or too advanced.
But, it’s way easier than it sounds—and I’ll show you exactly how to do it without a thermometer, no stress required.
How It Holds Up in the Heat (Yes, I Tested It in Florida)
I knew that if I was going to test and share this recipe I had to put it up to a heat test and see how it did on an 89° hot and humid South Florida June day. I’m SO excited to tell you that after one hour of it being in the shade outside, it still looked freaking fantastic.
Check it out!
I then moved the cupcake over to being in the direct sun, and that’s when it started to melt, about 15 minutes in. So as long as you keep your cake in the shade, I would expect it to keep it’s shape for a few hours- yes even in 90° heat and humidity.
What is this sorcery you might ask? 🤣 A few things:
- My secret weapon = Cornstarch in the sugar. Using just 1 tbsp of cornstarch added to the sugar helps with stability in humid and high heat situations all without sacrificing the flavor. You won’t even know its there.
- Slightly less butter- this recipes uses slightly less butter than other recipes so it keeps it from softening too much.
- Keeping the butter at room temp but not too soft. The butter should still feel cool to the touch, not melty or greasy. If the butter is too warm it can turn your SMBC soupy.
First Steps: Combining Egg Whites and Sugar
First things first, make sure your equipment is clean from any grease or fat. If theres even a speck of it on the bowl or attachments, the egg whites won’t whip.
I take a paper towel with some white vinegar on it and wipe it over everything before starting. You can also use a half lemon and swipe it all over.
Whipping the meringue
The mixture is ready when all the sugar is melted and the mixture is a lot lighter and thinner, not glue like. Take the bowl off the double boiler and move to the stand mixer with a whip attachment.
Next add in the vanilla extract and salt. Whip for 15 seconds on high and you did it!
Troubleshooting
If your frosting looks curdled, chunky, or soupy- dont panic, there is a fix for everything!
Curdled or chunky? Your butter was probably too cold (you didn’t over whip it dont worry) or you just need to keep whipping- sometimes this can happen! Just keep whipping for a few more minutes to help it soften, or put the bowl back on the double boiler to warm the bowl slightly just 5- 10 seconds, any longer will melt the butter and then you’ll have soup.
Soupy? If it looks soupy or runny, it’s likely too warm. Stick the whole bowl in the fridge for 10–15 minutes but no longer or it will be too thick. Then rewhip until it comes together.
The Swiss Meringue Buttercream I Can’t Stop Making
Ingredients
- 5 egg whites, room temperature -large- about 150g
- 2 cups granulated sugar, 400g
- 1 tbsp corn starch
- 1.5 cups unsalted butter, cold but pliable- 3 sticks(340g), diced small
- 2 tsp vanilla extract
- 1/4 tsp kosher salt
Equipment
- 1 Double boiler
Instructions
- Wipe down your mixing bowl and attachments with white vinegar or a half lemon to degrease.
- Heat a small pot with 1-2 inches of water and bring to a simmer. Add 5 large room temperature egg whites to the mixing bowl along with 2 cups of sugar and 1 tbsp corn starch. Place the mixing bowl over the simmering water. The bowl should not touch the bottom.
- Whisk the mixture constantly. At first, it’ll look thick and gluey, but it will start to thin out as it warms. The goal here is to melt all the sugar. To check, rub a bit between your fingers—it should feel completely smooth with no graininess. If its still grainy, keep whisking. This can take 10-12 minutes.
- Remove the bowl from the heat and transfer it to your stand mixer fitted with the whisk attachment. Beat on medium speed for 10–15 minutes, until the bottom of the bowl feels cool to the touch and stiff peaks form. It needs to be fully cooled down before you add the butter.
- With the mixer on medium high speed- add in the diced butter 1 tablespoon at a time making sure it's fully mixed in before adding more. Repeat till all the butter is used.
- Add in the 2 tsp vanilla extract and 1/4 tsp salt and mix for 15 more seconds on high.
- Frost over vanilla cupcakes.
