Swiss Meringue Buttercream is my absolute go-to frosting – and as fancy as it sounds, it’s actually surprisingly simple to make.
There are a few steps involved, but once you get the hang of it, you’ll realize just how easy it is.
Once you’ve tried SMBC, you’ll never go back to American buttercream. This buttercream is soooo much silkier, smoother, and WAY less sweet than typical buttercream.
Check out just a few of the cakes I’ve made over the years using this recipe:
The Butter for Swiss Meringue Buttercream
I prefer to use unsalted butter in all my baking and buttercreams. Salted butter contains varying levels of salt, so one brand can have double the salt content as the next brand. I stick to unsalted, so I stay in control of how salty everything is.
Be sure to bring your butter out well ahead of making Swiss Meringue Buttercream. You want the butter to be softened to room temperature – around 70°F / 21°C. Slice the butter into Tablespoon-sized pieces. This allows the butter to come to room temp faster, and also allows it to emulsify with the meringue quicker than throwing a whole stick in.
Please don’t be tempted to microwave your butter to get it to the right temp faster, as melted butter could ruin your buttercream.
Do I Need to Add One Piece of Butter at a Time?
No! I’ve seen loads of recipes instructing you to add one small piece of butter at a time, but I’ve never found this to be necessary. As long as your butter is soft, it’ll combine with the meringue just fine. Sure, it may look curdled for a moment, but I promise, it’ll come back to a smooth, cohesive buttercream with continued beating.
How Many Eggs do I Need?
Because this recipe needs a very specific ratio of ingredients, I have given a weight for the egg whites, rather than a number. Egg sizes vary from country to country, and it’s far more accurate to weight your egg whites.
Kiersten’s Tip: Anytime I bake a recipe asking for an extra egg yolk, I place the leftover egg white in a labeled Ziploc bag in my freezer. I then accumulate these egg whites over time, so whenever I need to make SMBC, French Macarons, or meringues, I have a stash I can just thaw, measure, and use! Egg whites freeze and thaw perfectly, so this tip comes in handy for me time and time again.
Can I Use Pasteurized Egg Whites?
I have successfully made Swiss Meringue Buttercream using bottled, pasteurized egg whites. Just note that they may not froth up the same way, as they’re not designed to hold shape for purposes such as this, so for best results, use real eggs. Separate your eggs while cold, and then bring to room temperature before starting the buttercream.
Please note, if you’re looking to use pasteurized egg whites so they’re safe for consumption, there’s no need here, as we’re cooking the eggs to 160°F / 71°C. Eggs are safe for consumption after hitting that temp.
Do I Need a Thermometer?
Yes. You can use a candy thermometer, but I find an instant-read thermometer works just as well.
Do I Need a Stand Mixer? Can I Use a Handheld Electric Mixer Instead?
I find a stand mixer is best for making SMBC. You can use a handheld electric mixer, but the entire process will take much longer.
Can I Halve This Buttercream? Can I Double This Buttercream?
Yes, you can halve or double the Swiss Meringue Buttercream recipe – just stick to the proportions exactly, and follow the same directions. Please note that doubling this recipe will cause a standard stand mixer bowl to be very full, but it shouldn’t overflow.
Help! My Swiss Meringue Buttercream is Curdling or Separating!
Do not panic! This is normal. Many things may cause the buttercream to separate, such as butter being too cold, adding too much flavoring at once, and temperature changes. Simply keep mixing and it will come back together and be silky-smooth.
If the SMBC seems thin or runny, refrigerate for 10-15 minutes before continuing mixing with the paddle attachment, on low speed, until it comes together.
If the mixing bowl feels cold and your buttercream is separating, take about 1/2 cup of buttercream and microwave until melted. Stir until smooth, then run your mixer on low while pouring the melted mixture back into the bowl. This should help bring down the overall temperature of the buttercream and allow everything to emulsify.
If in doubt, just keep mixing! I once added way too much pureed cherry to my SMBC at once, and it curdled and looked awful. I thought I’d ruined it, but after about 30 minutes of mixing on low, it all came back together and looked (and tasted) perfect! So channel your inner Dory (or her baker alter-ego) and “just keep mixing!”.
How to Store Swiss Meringue Buttercream
Store Swiss Meringue Buttercream inside an airtight container in the fridge for up to one week. SMBC can also be frozen inside an airtight container for up to 3 months. To thaw, place in the fridge overnight, then bring to room temperature and beat on low with the paddle attachment until creamy before using.
Ways to Use Swiss Meringue Buttercream:
- Frost Vanilla Cake
- Ice Vanilla Cupcakes
- Fill Dark Chocolate French Macarons
- Spike with Irish Cream and pipe on Chocolate Stout Cupcakes!!
Swiss Meringue Buttercream
Ingredients
- 177 grams egg whites, at room temperature
- 200 grams (1 cup) granulated sugar
- 1/8 teaspoon salt
- 454 grams (1 lb) unsalted butter, at room temperature, cut into cubes
- 1 Tablespoon vanilla extract, (or any other flavorings you like!)
Instructions
- In a medium saucepan, place about an inch of water and bring to a boil, then reduce to a simmer. In the bowl of your stand mixer (or a large metal mixing bowl that fits nicely over your saucepan), place the egg whites, sugar, and salt, and whisk a little to combine. Place the bowl over the pot of simmering water.
- Continue to lightly whisk, keeping the mixture moving, to prevent scrambling the eggs. Around 140°F / 60°C, the sugar will dissolve and the eggs will begin to froth and foam up.
- Once the mixture has reached 160°F / 71°C (usually about 3-5 minutes), remove the bowl and carefully wipe the bottom dry.
- Place the bowl on a stand mixer, fitted with the whisk attachment. Beat on medium-high until stiff peaks form, and the outside of the bowl is completely cool to the touch. This usually takes me about 10 minutes. Ensure you have reached stiff peaks before proceeding to the next step.
- (How to Check for Stiff Peaks: Remove whisk attachment and turn it upside down. The meringue on the whisk should stand straight up, or with just a very slight bend. If the bend is more significant, whisk for another minute at a time until the bend is very slight or straight up.)
- Swap to a paddle attachment and add all your butter at once (ensure your butter is at room temperature – 70°F / 21°C is perfect).
- Mix on the lowest setting on the mixer, until beautifully silky-smooth. This sometimes takes awhile. It may start to separate or look curdled, but just leave it alone and keep mixing on low – it will fix itself, I promise!*
- Once you have light, fluffy, completely-smooth buttercream, add the vanilla and/or other chosen flavorings.
- Use to frost or fill your baked goods, or store Swiss Meringue Buttercream for 1 week inside an airtight container in the fridge. Just pull it out and let it come to room temperature, then re-beat on low again to refresh, before using. It may separate again, but it will come back together.
