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Frosting Recipe,

How to Make Swiss Meringue Buttercream

by Katherine Walton on May 18, 2022 37 Comments

This is my Swiss Meringue Buttercream recipe with a Walton Twist. If you are familiar with my content on my Instagram account which you can see here you will know that I like to challenge new ideas on the way traditional recipes are made.

I make my Swiss Meringue Buttercream recipe a little different to how a traditional recipe is made. The main difference is that I beat the butter separately and then I add the Swiss meringue to the beaten butter and mix them together at the end. You can watch my full step by step how to video of my Swiss Meringue Buttercream recipe bellow. Swiss Meringue Buttercream – Full Step by Step Guide


  • 185 grams of fresh egg whites at room temperature (egg whites of 4 Jumbo eggs)
  • 370 grams of caster sugar (1 2/3 Metric cups)
  • 370 grams of unsalted butter at cool room temperature but soft
  • 2 teaspoons of clear vanilla extract or any other flavour
  • Digital food thermometer


  1. Fill a medium sized saucepan with about 2 centimeters of water. Bring to a boil then reduce to medium heat.
  2. Place egg whites and caster sugar in a clean heat proof  stand mixer bowl. Make sure bowl is completely free of grease. If in doubt wipe with white vinegar or lemon juice. Whisk together until all incorporated, then place bowl on top of sauce pan. Make sure the bowl does not touch the water.
  3. Whisk and mix ingredients until sugar dissolves completely. Scrape the bowl on the sides with a silicone spatula so that all the sugar dissolves with the egg whites.
  4. Temperature should reach 74 degrees Celsius (165 Fahrenheit). If you do not have a food thermometer you can rub the mixture between your fingers and you should not feel any sugar granules. The mixture will also change and become runny and foamy. (You can watch how it changes on my Step by Step video above).
  5. Transfer bowl to stand mixer and mix at medium-high speed until the meringue starts to come together. It should become thick and glossy and increase in volume. The meringue should not be runny or fall from an upside down spoon.
  6. Transfer meringue into another large bowl. Set aside until it has completely cooled to room temperature.
  7. Wash mixer bowl and add unsalted butter and mix at high speed until butter changes colour to a very pale cream and it increases in volume. It can take up to 10 minutes or more. You must scrape the sides off the bowl to ensure all butter is beaten.
  8. Once butter reaches the desired consistency, mix in the meringue and mix together from medium to highest speed for 5 minutes.
  9. Add 2 teaspoons of desired flavouring and continue to mix on high speed for 2 minutes.
  10. Add food colouring if desired.


How are the ingredients measured in this recipe?

In this recipe and in all of my recipes I provide all ingredients in grams and in mL (millilitres) where applicable. I also provide the ingredient quantities in METRIC cup measurements. However, be aware that cup measurements and spoon measurements vary in different countries. Therefore, I highly recommended the use of scales where applicable to measure ingredients to achieve exactly what the recipe intends.

What is caster sugar and can I substitute it in this recipe?

Caster Sugar is also known as super fine granulated sugar. Not to be confused or replaced with icing sugar also known as powdered sugar and confectioners’ sugar. You may replace the caster sugar with standard granulated white sugar in this Swiss Meringue Buttercream recipe as the sugar is dissolved in the egg whites when cooking.

What does cool temperature but soft butter mean?

The butter must be cold to the touch but soft. That means you should be able to press with your finger and make an indentation. If the butter looks like it is melting or too soft, you can put it back in the fridge until it feels cold to the touch again and firms up a little bit. Five minutes should suffice.

How to separate egg whites from egg yolks?

It is best to separate the egg whites from the egg yolk when the eggs are cold. Then leave the egg whites in a bowl covered to bring to room temperature.

Do I need to use a food thermometer?

I recommend the use of a digital food thermometer in order to know if the temperature of the egg whites and sugar has reached 74 degrees Celsius (165 Fahrenheit). Egg safety guidelines state that bacteria such as Salmonella is killed when eggs are heated to 74 degrees Celsius (165 Fahrenheit).

How to store this Swiss Meringue Buttercream and what is its shelf life?

This frosting can be kept at cool room temperature for up to 3 days. It can be kept refrigerated for up to 5 days. Bring to room temperature before use. You can re whip with a metal spoon, or with a mixer.


The Swiss Meringue Buttercream becomes runny when I mix the meringue and the butter. What can I do to prevent it and fix it?

There are a few factors that can directly affect the stability and the end result of this Swiss Meringue Buttercream.

The first thing is to make sure that the frosting has the right ratio of butter to meringue to successfully achieve a stable, easy to pipe and silky Swiss Meringue Buttercream. The butter is the key ingredient that gives this Swiss Meringue Buttercream its structure and firmness. Using less butter than what is required for the amount of meringue in this recipe may yield a runny frosting.

It also very important to make sure that the meringue has completely cooled before adding it to the beaten butter. A warm meringue will “melt” and soften the butter, which will make it difficult to achieve a firm frosting. You can refrigerate the meringue while the butter is being beaten if you wish to speed up the process. You may also refrigerate the runny frosting for five to ten minutes and beat it again in the mixer.

Other small factors such as mixing the frosting in warm bowl can affect how well the Swiss Meringue Buttercream comes together. Also preparing the Swiss Meringue Buttercream in a warm or hot room can also affect the end result and could yield a frosting that does not firm up or appears runny or lumpy as if the ingredients are not incorporating together.

Watch the full step by step video provided with this recipe for visual instructions. If you have any questions leave me a comment and I’ll be more than happy to guide you through.


  1. Pingback: Pink Ombre Rosette Cake Using Wilton Tip 1M – Walton Cake Boutique
  2. I can’t tell you how much I LOVE THE RECIPE!!! It is fool proof and fail safe. Your take on making this silky, sinful, decadent frosting is genius!!! Every time I make it I send a little love your way!!! THANK YOU!!! XOXO

    1. Hi Tina 😊, Yes it is enough to layer and frost it as well. As long as the cake isn’t taller than 4″. Then you may need to make extra but also make extra if you’re going to pipe swirls for example.

  3. Hello. How do you color SMB? Exactly at what stage and how to get the rich colors with gel colors?

    Alsoo is this recipe enough to pipe rosettes?

    1. Hi 😊, you can colour Swiss Meringue Buttercream immediately after making it. However, you will tend you get deeper colours if colouring the frosting the day after. In saying that the type of food colouring and brand play a big part. Some brands work better and give deeper more vibrant colours. I use Rainbow Dust Progel to colour my Swiss Meringue Buttercream for rich colours. You can colour immediately. You will also find that the colours will always deepen after a few hours. So it’s a good idea to wait and see if you need to add more colour.

  4. Hi! I just want to say that this recipe is PERFECT. I’ve had a fear of making it for years and my first try with it was so wonderful. Thank you

    1. Hi😊, thank you so much! I appreciate your feedback. So glad it worked for you. It is one of those frosting recipes that makes you hesitate making as it’s not as simple as a standard buttercream.

  5. I’m interested to try your recipe as we’ve had a lot of very hot weather in the UK recently and my SMBC suffered even though I kept chilling and re-whipping it. What makes your recipe more heat stable? Is it linked to the whipping of the butter and adding the meringue to it? Or is the ratios of the ingredients? Or something entirely different?!

    1. Hi Sharon 😊, yes the main reason is that I add the cooled meringue to the beaten butter as opposed to adding chunks of butter to the meringue. Also the ratio of the ingredients themselves. Any less butter and you would end up with a soup like consistency. The butter gives the frosting its structure. You will also find that once the frosting is made and turns out as it is shown in the video. The frosting itself will stay that way. If you find that any frosting such as Swiss meringue buttercream or Italian buttercream curdles or doesn’t come together as it should from the start, it will usually be due to issues with the butter, such as it being too soft or melted from the start, or the meringue not having cooled before mixing with the butter or the meringue not reaching medium to stiff peaks. In those circumstances you can try to refrigerate the frosting and try mixing again, however once you have tried a few times you’ll find it is not salvageable.

      1. You’re very welcome and please let me know how it is goes if you change the ratios to suit your taste 😊

  6. HI I live in Belize its summer all year round and over here buttercream icing is not recommend for cakes too hot and humid. Im looking for a stable frosting for a wedding cake this October the event will be outside,i was wondering how i can make your recipe with less butter since butter is not good for the heat, thanks

    1. Thank you Katherine! I guess I need to give it a try and see if the sweetness vs butteriness is right for my taste too – currently the ratios I use are 200g whites, 250g sugar, 425g butter which has a creamy flavour but is not too buttery. This yields about 850g of buttercream.

      1. Hi 😊, I have used my Swiss Meringue Buttercream in the middle of summer here in Sydney in over 40 degrees Celsius and humid weather. So it can withstand heat. I do recommend if possible to keep the frosted cake in a cool room but not in the fridge unless the cake will be served immediately. Cakes can have condensation when they are moved from the fridge to a warm room making the frosting seem like it’s melting. Adding less butter is not recommended as the butter helps the frosting hold its shape and give it structure. Without enough butter you will end up with a soup like frosting.

  7. Hii!
    How to make chocolate swiss meringue buttercream and also how to add liquid colouring for this swiss meringue buttercream 🤗

    1. Hi 😊, you can mix my chocolate ganache straight into my Swiss Meringue Buttercream https://waltoncakeboutique.com/chocolate-ganache/ or you can add 1/4-1/2 cup of cocoa powder at the end of the recipe and mix well in the mixer. You can use liquid food colouring to Swiss Meringue Buttercream, 1 teaspoon at a time depending on the colour you want to achieve. However, oil food colouring or concentrated gel food colouring is better for best results.

  8. Hi!
    I love this recipe! I was wondering if it’s possible to successfully add things such as lemon curd or caramel to it to achieve different flavours? If so, how much would you suggest adding?
    Helen x

    1. Hi Helen 😊, thank you so much for trying it!. You can certainly add lemon curd or caramel. Swiss Meringue Buttercream is very forgiving. I always start with about 1/4 cup of ingredients such as caramel or lemon curd to check for taste. You can then add more if necessary. The only thing to keep in mind is that acidic ingredients such as lemon can cause the frosting to curdle. So adding smaller amounts at a time to test is always best.

  9. Hi! Thank you for sharing your recipe. This by far gave the best results in terms of stability since our place is pretty hot and humid. Would it be okay though to reduce the amount of sugar?

    1. Hi 😊! you are very welcome and thank you for trying my recipe. So glad to hear it worked for you. Reducing the amount of sugar would affect the stability of the meringue and hence the overall frosting so I wouldn’t recommend it if you make in a warm environment. In saying that, I always say that there is no harm in trying something different to see how it goes. If you do reduce the amount of sugar let me know how it goes!

  10. Hi, I just found your recipe on YouTube. I wanted to ask if separate beating of the butter makes this more stable than the normal Swiss meringue?
    Thanks in advance.

    1. Hi 😊, it makes it a lot less likely to curdle or separate when mixing them together, which can occur when you add the chunks of butter into the meringue in other methods, making it more stable.

  11. Hi Katherine, I love this recipe but, for some reason, I couldn’t get mine to smooth out completely on my cake. I had a crumb coat and then added a final coat. I’m assuming it had something to do with the cake being too cold or my room being too cold or even that I didn’t add enough buttercream for a final coat. Still learning so would love some help, please 😊

    1. Hi Natalie!, just seeing your message now! Did you refrigerate the cake after the crumb coat and consecutive coats? Also have you tried using a hot scraper to smooth the final coat? I have a really good tutorial on my Youtube channel on how to smooth a cake. It works for both buttercream other frosting recipes. https://youtu.be/w6Jw-GAXNXo

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