Swiss Meringue Buttercream, Revisited {SMBC Recipe 2.0} (2024)

Are you keen to pipe buttercream like a professional?
Or to smooth icing like a star??
Do you want a buttercream that doesn’t taste gritty, just smooth and not too sweet???

Then you need Swiss meringue buttercream in your life, and this post is for you 😉

I’ve been waxing lyrical about Swiss meringue buttercream {SMBC or just ‘SMB’} for a wee while now. It gets a bit of stick for being more time consuming and a bit trickier than ol’ American buttercream: butter, icing sugar, vanilla, you’re done! But after a couple of goes I think SMBC is just as straight forward – and it all comes down to your confidence! So if you’re a newbie cake decorator and worried about trying it, face your fears and have a go 😉 Plus it’s totally worth the effort for the fabulous flavour, pipe-ability and stability it offers…

I’ve realised that my go-to recipe for SMBC has changed over-time and so this post is as much for me (to record where my process is at) as it is for sharing with you.I got my start in the ways of meringue buttercream for Rosie of Sweetapolita fame, and it was her recipe I adapted forthis post in 2014{!}. I then moved on to the easier‘no meringue’-SMBC methodpopularized by Summer Stone. But then I was converted by BraveTart (Stella Parks) by her scientific method for SMBC as perher Serious Eats recipe.My current favourite version of SMBC follows Stella’s method except I don’t heat the egg whites higher than needed to pasteurise them (71°C).

Note (equipment): Now is the time to shell out for a sugar thermometer! If you’re getting serious enough about cake making to try this recipe out, it’s a small price to pay for good accuracy in baking (and cooking for that matter). I started off with this one{before I got my Thermapen<3} and it’s a perfectly respectable thermometer for this and many other recipes and costs less than $NZ15.

Also note (butter vs shortening): I swap in Kremelta (shortening) for half the butter to make the buttercream less yellow, making it a nice light natural colour, and easier to mix truer tones with gel colouring (especially those tricky blues and reds!). But if you prefer the colour and / or flavour of butter-only icing then by all means just use good old dairy for both quantities below.

Swiss Meringue Buttercream 2.0

Adapted from Serious Eats / BraveTart. Makes approximately 3 cups.

This recipe uses the following key ingredient proportions which can be applied if you have different quantities of the ingredients:

Egg whites : Butter : Sugar – – 1 : 2.5 : 1.8

• 170g egg whites (from approximately 5 large eggs, or pasteurised egg whites from a carton)
• 310g sugar
• 215g butter, cut into small (1/2 inch) cubes and brought to room temperature
• 215g Kremelta / Crisco / shortening,cut into small (1/2 inch) cubes
• 1 tsp natural vanilla essence
• a few drops of food colouring (if desired)

1. Heat egg whites and sugar: Place the sugar and egg whites in a metal bowl that you have previously wiped with vinegar or lemon juice to remove any grease residue.Note: this can be your stand mixer bowl (if it’s heatproof) but doesn’t have to be as you may want to strain the cooked sugar-egg mixture before the next step.Sit the bowl on a small saucepan filled with an inch or so of water, so that the bowl is just sitting above the water.Heat the saucepan over a moderate-high heat to bring it to a simmer (not boiling too vigorously), stirring the egg white and sugar mixture continuously with a spatula. Make sure you constantly scrape the base of the bowl to ensure all the sugar has dissolved in the egg white, and to avoid letting any of the egg white cook too quickly! Continue to stir until the mixture has heated up to 71°C on your sugar thermometer, which can take between 10 and 15 minutes depending on the heat under the pot. Pour the mixture into your stand mixer bowl (if not already).You’ll know it’s getting close when the mixture becomes a bit darker and lots of bubbles form on the surface. If you notice some (unavoidable) bits of cooked egg in the final mixture, you can strain them out by pouring the mixture through a metal sieve into your mixing bowl.
2. Beat egg white-sugar mixture: Using the whisk attachment for your stand mixer (or with beater attachments if using a hand mixer), whip the mixture at the highest or second highest speed until it forms stiff peaks – pulling the whisk away from the final mixture will leave little peaks that don’t fall back on themselves – and the mixture has cooled down so that the bowl doesn’t feel warm to touch. This will take at least 10 minutes, and the mixture is now a Swiss meringue.
3. Add butter to meringue: This is the ‘scary’ part… deflating the meringue with butter and shortening! Using a beater attachment (continue with beaters if using a hand mixer) and mixing at a moderate speed, begin adding the butter and shortening a few cubes at a time and approximately 30 seconds between additions. The meringue will become loose and runny at first (see first picture below), then it will gradually thicken (picture 2), and when almost all the butter and shortening is added it may look grainy and blotchy with uncombined butter (picture 3) until… bam! it suddenly starts to clump together and thicken into one lumpy mass (picture 4). Once it has ‘come together’ like this, keep beating for another five minutes to allow it to smooth out like in the final two pictures.

4. Add vanilla and colouring, use or store: Beat in vanilla essence and any food gels that you want to use – start with just a few drops and beat until you know how dark the icing will be, before adding more colouring.SMBC can ‘hold’ quite a lot of liquid, so you can add flavourings including fruit purees, cooled melted chocolate etc, add 1/4 cup at a time and beat well after each addition.You can use your SMBC straightaway, or store (in an airtight container or sealed bag) at room temperature for the rest of the day, in the fridge for a week, or in the freezer for three months. If your SMBC comes from the fridge or freezer, bring it back to warm room temperature before using – I like to do this by placing the container it’s in into a sink of warm water to sit for an hour or so.

Troubleshooting: What makes SMBC intimidating is its sensitivity to temperature – too cold and it will be greasy and congealed {ick}, too hot and it will be runny and lumpy {like cottage cheese}. No matter how bad your SMBC looks, promise me you will keep telling yourself I can fix this icing!!!It’s actually very forgiving – most issues with SMBC are due to the ingredients not being emulsified (combined) properly, which can be fixed in the following ways…

For too-cold, curdled / separated SMBC… this often happens during winter when the air (and butter) temperature is low.Remove around one fifth to one quarter of the buttercream and place in a microwave proof container. Heat on high for 10 seconds at a time until the buttercream has visibly softened and started to melt around the edges. With the stand mixer operating at low speed, beat the buttercream that is still in the bowl while slowly adding the heated buttercream. Beat for a couple of minutes and the buttercream should come together; if not, repeat this step up until it does work!It might sound strange to microwave buttercream, but this has worked many times for me – the temperature of the SMBC in the mixer bowl gradually increases to a suitable temperature for emulsification B-)

For too-warm, runny and lumpy SMBC… this can happen in summer or in a warm room, causing the butter to heat up too much.Place the mixer bowl of buttercream in the fridge for 10-15 minutes, then remove and beat again. Repeat until the SMBC has cooled enough to come together.

Have you tried SMBC? What did you use it with – cake, cupcakes, cookies? How did you decorate with it?