Perfect Swiss Meringue Buttercream (A Complete Guide)

Swiss meringue buttercream is by far my favorite frosting for cakes. Dare I say… it is probably the most significant recipe I’ve learned to level up my cakes. It looks professional and is lighter in texture and taste than American buttercream.

Swiss meringue buttercream is made with egg whites, sugar, and butter. The egg whites and sugar are cooked over a water bath and whipped into a meringue. Next, the butter is added and mixed in, creating a light yet stable buttercream that pipes and frosts smoothly for layer cakes.

The key to perfect Swiss meringue buttercream is learning the visual cues of three parts of this process. I’ll show what each one looks like so you can confidently move on to the next part and get perfect buttercream every time.

What ingredients go into Swiss meringue buttercream?

  • Egg whites - the translucent and dense part of the egg minus the yolk. They’re mainly composed of water but also egg white proteins. These proteins are critical structural components to meringues - they form a super sturdy network that inflates and holds air well. (That’s why whipping a meringue almost triples in volume!)

    And yes, you’ll probably have lots of yolks leftover, but I just keep mine in a container in the fridge for pastry cream or my buttery vanilla yellow cake.
  • White granulated sugar contributes to this buttercream’s delicious sweet taste and supports the air needed to make the meringue.
  • Cream of tartar is an acidic ingredient that helps unstick the sticky egg white proteins in the white from each other, yielding a fluffier meringue. If you don’t have access to this, you can sub lemon/lime juice. Just double the amount listed in the recipe.
  • Unsalted butter contributes to the body of the buttercream. Butter contains almost 80% fat, which is why it’s so easy to smooth on the outsides of cake. It also includes a particular protein called an emulsifier, which holds fat and water-based ingredients together. This is super important since this buttercream is emulsion based. (I’ll get into that later, but if you’re curious about what is going on, I will go into further detail in my video below.)
  • Flavorings (Vanilla Extract/Salt) provide the overall flavor profile of the finished buttercream. Any extracts can be used, but my recipe below is vanilla.

How much Swiss meringue buttercream do you need for cakes and cupcakes?

I have a handy reference on how much frosting you’ll need for cakes. These amounts are pretty generous. For cupcakes, this accounts for a swirly piped design (such as a rosette with a Wilton 1M). For cakes, this includes enough frosting for filling, crumb coats, top coats, and some minor piping on the tops.

FROSTING AMOUNTS NEED FOR CAKES AND CUPCAKES:
  • 12 cupcakes - 3 cups
  • 24 cupcakes - 6 cups
  • cake, 6 inches with two layers - 3 cups
  • cake, 6 inches with three layers - 4.5 cups
  • cake, 8 inches with two layers - 6 cups
  • cake, 8 inches with three layers - 7.5 cups
  • cake, 8 inches with four layers - 9 cups

Now if you don’t want to do any of the math, I built the Cakeculator, which calculates my recipes based on the cake sizes you’re baking. You can use it here.

How to store cakes with Swiss meringue buttercream?

I store cakes with Swiss meringue buttercream for up to 2 days at room temperature (unless they have pastry cream fillings or fresh fruit, which need refrigeration). The egg whites are cooked, and the buttercream contains a fair amount of butter and sugar, which is generally safe to store at room temperature. If you are uncomfortable with that, feel free to pop your frosted cake in the fridge.

The buttercream will get super firm in the fridge (after all, it is mostly butter). I like to wait until the buttercream has firmed, remove it from the refrigerator, wrap it in plastic, and then put it back. This protects the cake from any odors. You can store a cake like this for days, maybe even a week or two. The frosting is a thick coating of fat and prevents moisture loss from the interior cake.

You can also freeze whole buttercream cakes - frosted and all. Do the same thing - let it firm up, then wrap it in plastic.

How to store cakes with Swiss meringue buttercream?

I store cakes with Swiss meringue buttercream for up to 2 days at room temperature (unless they have pastry cream fillings or fresh fruit, which need refrigeration). The egg whites are cooked, and the buttercream contains a fair amount of butter and sugar, which is generally safe to store at room temperature. If you are uncomfortable with that, feel free to pop your frosted cake in the fridge.

The buttercream will get super firm in the fridge (after all, it is mostly butter). I like to wait until the buttercream has firmed, remove it from the refrigerator, wrap it in plastic, and then put it back. This protects the cake from any odors. You can store a cake like this for days, maybe even a week or two. The frosting is a thick coating of fat and prevents moisture loss from the interior cake.

You can also freeze whole buttercream cakes - frosted and all. Do the same thing - let it firm up, then wrap it in plastic.

I store cakes with Swiss meringue buttercream for up to 2 days at room temperature (unless they have pastry cream fillings or fresh fruit, which need refrigeration). The egg whites are cooked, and the buttercream contains a fair amount of butter and sugar, which is generally safe to store at room temperature. If you are uncomfortable with that, feel free to pop your frosted cake in the fridge.

How to store cakes with Swiss meringue buttercream?

I store cakes with Swiss meringue buttercream for up to 2 days at room temperature (unless they have pastry cream fillings or fresh fruit, which need refrigeration). The egg whites are cooked, and the buttercream contains a fair amount of butter and sugar, which is generally safe to store at room temperature. If you are uncomfortable with that, feel free to pop your frosted cake in the fridge.

The buttercream will get super firm in the fridge (after all, it is mostly butter). I like to wait until the buttercream has firmed, remove it from the refrigerator, wrap it in plastic, and then put it back. This protects the cake from any odors. You can store a cake like this for days, maybe even a week or two. The frosting is a thick coating of fat and prevents moisture loss from the interior cake.

You can also freeze whole buttercream cakes - frosted and all. Do the same thing - let it firm up, then wrap it in plastic. People worry about freezing cakes, but I did a study on it - the effects are minimal.

In fact, this is how cakes are shipped. Once, I got a super fancy cake from a famous bakery as a gift from TikTok (Lol… I have no idea why they decided to send me a cake, but I’m not one to turn down sweets…). It arrived rock hard, frozen, surrounded by ice packs. And it tasted AMAZING when it thawed.

Step-by-Step

How to make my Swiss meringue buttercream frosting

Step 1. Prepare the double boiler.

Take a pot with water and set it to a slight simmer. I use a steamer basket because my pot is too big, and the bowl would sit in the water. You want your bowl as close to the surface of the water without touching it.

Step 2. Stir together egg whites, sugar + cream of tartar.

Use a spatula and stir together the whites, sugar, and cream of tartar. It will be super thick, yellow, and grainy from the sugar.

Step 3. Cook the egg whites.

Cook while scraping with the spatula until the meringue reaches 165°F /74°C. This pasteurizes the eggs or kills off any food-borne pathogens present in the egg whites.

Step 4. Whip meringue. VISUAL CUE ONE

Take those whites (careful the bowl may be hot!) and whisk for 10 minutes. Did you get a super fluffy and white meringue? That means you can move onwards!

TROUBLESHOOTING:

If your meringue remained liquid or your meringue is droopy, you have a couple options. You can move on to the next step, but you may need more butter to bring everything together. The other option is to start over, ensuring there was no residual fat (oils, batter) or detergent in your bowl and/or yolk in your egg white when you cracked your eggs. Fats and detergents break up air bubbles and won’t let the meringue get fluffy or trap air.

Step 5. Add butter. VISUAL CUE TWO

Cool the meringue and add the butter in, one chunk at a time.

When the buttercream comes together or emulsifies, it will thicken substantially. It may still be chunky and riddled with air pockets because we’re using the whisk attachment, but it should have the texture of a super light, airy butter.

TROUBLESHOOTING:

adding the butter, it looks greasy, brokenIf you find that after you add the butter, it looks greasy or broken, or soupy, see the “Troubleshooting Swiss Meringue Buttercream” section below.

Step 6. Add flavor + smooth. VISUAL CUE THREE

Switch over to the paddle attachment and add your flavorings. The visual cue for this part is to make sure the buttercream is super smooth. Taste to see if it’s yummy enough!

TROUBLESHOOTING:

If you find that your buttercream is riddled with air pockets, continue to mix with the paddle attachment. When I’m about to frost a cake, particularly the top or outer coat, I mix my buttercream right before frosting. I’ll let it go on the mixer on the lowest speed setting for at least 5-10 minutes to ensure it’s super smooth. It just makes our job easier to smooth everything out.


Step 7. Use or store in the fridge/freezer.

Look at how smooth and yummy! You can use this right away or package it up in containers to save for later.

Troubleshooting Swiss Meringue Buttercream

The most common issue that bakers tell me about when making this buttercream is that it is either curdled, broken, or soupy. Don’t throw out your buttercream, please! It’s fixable due to the temperature of the butter.

I wrote a whole post on it here with pics to illustrate the process so please check it out if you’re having issues.

Ok, I think you’re ready to make some buttercream!

If you are a visual learner, check out this video below and I'll show you each and every step to make my buttercream. If you're ready to get started, I have my Vanilla Swiss Meringue Buttercream recipe below.

Hi! I'm Adriana.

I built this site for the curious home baker. I'm a huge science + tech nerd; you'll feel right at home if you like exploring and experimenting in the kitchen too.

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