Name: Swiss Meringue Buttercream
Prep time: 10 min
Total time: 30 min
Ingredients: 1 cup sugar; 5 large egg whites; 1 pound unsalted butter, softened and cut into 1 inch pieces (see notes for salted butter); 1 tsp pure vanilla extract; pinch salt

Swiss Meringue Buttercream Frosting is a silky smooth frosting with just a touch of sweetness. Using egg whites, sugar, and butter it's a stable frosting perfect for piping on cakes and cupcakes.

If you're not familiar with this classic frosting, Swiss Meringue Buttercream uses egg whites heated with sugar, and then cooled and whipped with butter. It's similar to Italian Meringue Buttercream but instead of using a hot sugar syrup to heat the egg whites, the egg whites are heated with the sugar over a double broiler.

Unlike traditional American buttercream frosting, which is mainly butter and powdered sugar, this frosting is much less sweet and does not crust over. It also lacks that gritty or grainy texture often associated with American buttercream frostings.

It has a signature smooth and silky texture, plus it is a very stable frosting for piping, and holds up extremely well in the heat, which is why it's a common choice for patisseries and wedding cake shops for fancy cakes and desserts.

And, it's not nearly as daunting or complicated to make is you might think. It requires only 5 simple ingredients you probably already have on hand. If you've often thought that American buttercream frosting is too sweet, or you're looking to take your frosting up a notch, give this frosting a try!

Ingredients

Eggs: Fresh egg whites whip up much better than boxed egg whites, but boxed pasteurized egg whites can be used in a pinch. Just know that some brands whip up better than others.
Butter: The recipe calls for unsalted butter, but you can use salted instead, just omit the extra salt in the recipe.

How to Make

Step 1: Set up a double broiler

This recipe calls for a double broiler or bain-marie. This is much simpler than it sounds, and you don't need any special equipment. As long as you have a small or medium sized cooking pot and a medium or large metal or heatproof bowl, you're all set.

To use a double broiler, heat about an inch of water in the saucepan, and place a heat proof bowl over it as shown. Turn on to medium-low heat to simmer the water, making sure the water doesn't touch the bottom of the pan.

The water in the bottom of the pan creates steam to slowly and gently heat what is in the metal bowl. This method is very common for melting chocolate in addition to heating egg whites.

If you tried to heat either egg whites directly on the stovetop, without the double broiler, you'd have scrambled egg whites instead of warm egg white sugar mixture.

Step 2: heat egg whites

Mix the egg whites and granulated sugar in the heat proof bowl, and heat egg whites until they reach 160-165 °F, about 5-10 minutes.

The mixture doesn't get too hot so you can rub a bit between your fingers to make sure all the sugar has dissolved. Once the egg whites reach the correct temperature, remove from heat.

Step 3: whip egg whites

Once the egg whites reach the correct temperature, remove from heat. Add the heated egg whites to a bowl or standing mixer and beat the until they are cool. This takes longer than you think, about 10-15 minutes.

Step 4: add butter

Once they're cooled you change to a paddle attachment. Then and add the softened butter, one tablespoon at a time.

It might start to look curdled, that's fine! Just keep mixing. If it doesn't come together put into the fridge for 10-15 minutes to cool down and remix. Check out the troubleshooting section if you still have issues.

Once its comes together to a smooth frosting, add vanilla, pinch of salt, and any additional flavors or food coloring and remix. Thats it! The frosting is now ready to use on your favorite layer cakes, cupcakes, or desserts.

Flavor Variations

Like most buttercream frosting recipes, this is super versatile, and you can really flavor it up in so many different ways. I have a full post on Chocolate Swiss Meringue Buttercream, but here are a few easy add-ins to jazz up your vanilla frosting:

Lemon: Mix ½ cup homemade lemon curd into finished buttercream.
Nutella: Mix ½ cup Nutella into the finished buttercream.
Caramel: Mix in ½ cup caramel sauce into the finished buttercream.
Coffee/Kahlua: Mix 3 tbsp Kahlua into the finished frosting.
Bailey's: Mix 3 tbsp Bailey’s Irish Cream into the finished buttercream.

Tips for making this recipe

Make sure when working with egg whites that all of your tools are very clean. Any oil or butter on them can hinder the eggs white being whipped into stiff peaks.
Heat until the sugar in the egg whites until it is 160 ℉ and the sugar is completely dissolved. The mix never gets too hot, so you can rub a bit between your fingers to tell if the sugar is dissolved. If it still feels a little grainy, keep heating.
When using a double boiler, keep the water line below the bottom of the bowl you’re using to whip the egg whites. And, make sure it is on a light simmer rather than roiling boil. If the water line is too high and it touches the bottom of the bowl it can overcook the egg whites and/or make for a grainy frosting.
Make sure the egg whites have completely cooled before you add the butter, otherwise they can melt the butter and you won't be able to achieve optimal frosting.
If the buttercream curdles when adding the butter while you're mixing it, don't worry! This is totally normal and you just keep on mixing. It will eventually come together into a beautiful and silky final frosting.

Troubleshooting

No Candy Thermometer

If you don't have a candy thermometer, no problem! You can use boxed pasteurized egg whites in this recipe. Just beware some brands whip up better than others and you'll still need to heat up the egg whites to incorporate the sugar, but you don't worry about getting it to a particular temperature.

Egg Whites Won't Whip Up

Make sure the bowl is perfectly clean. Any oil in the bowl or on the utensils can cause the egg whites to not whip up properly. If using boxed egg whites, note some brands whip up more than others.

Curdled and Soupy Buttercream

It's very common for at some point when you’re mixing the buttercream for it to separate and look very soupy. This is common and does not mean you messed up!

Just keep mixing and eventually it will come together unto a soft silky buttercream.

If it’s not coming together, put it back in the fridge for about 15 minutes to firm it up and then re-whip. This can help accelerate the frosting coming together until a beautiful silky frosting.

Grainy Egg Whites or Frosting

Make sure the sugar has completely dissolved in the egg whites before whipping them up. Also, if the water in the double broiler touches the bottom of the bowl it can overheat the egg whites and cause the egg whites to get grainy, so make sure the water isn't too high.

What to do with egg yolks

Here are some fun recipes for all those egg yolks:

Homemade Lemon Curd
Pastry Cream (for Choux au Craquelin and tartlets)
Mini Fruit Tarts
French Canelé

Best Uses for Swiss Meringue Buttercream

This is a very common frosting for professional cake decorators, since it is so smooth, stable, and pipes so well. It’s great for piping flowers, painting on cakes, and using under fondant or homemade marzipan. It's also a great frosting for filling macarons.

Because it's such a common wedding cake frosting, you'll often see it paired in unique cake flavors like mocha, earl gray, or lavender.

It's also often paired with fresh fruit fillings like blackberries, blueberries, raspberries, and strawberries. But, it's still delicious with classic cakes and cupcakes like vanilla, chocolate,yellow cupcakes, and carrot cake.

Frosting Cakes and Cupcakes

This recipe makes about 3 cups of frosting. This is enough to cover about 2 dozen cupcakes (depending on how much frosting you use), a 9×13 inch cake, or a two inch layer cake.

As mentioned, it's a very stable frosting and stands up well in hot or warm weather. Frosted cakes and cupcakes can sit out for up to a day or so, provided there is nothing else in the cakes that would need refrigeration.

The frosting is hard and will taste very buttery when cold, so be sure to let any refrigerated and frosted desserts come to room temperature before serving.

Storing and Making Ahead

Like most buttercream frostings this frosting can be made ahead. It will last up to a week in the fridge or two months in the freezer in an airtight container.

When ready to use let defrost in the fridge if frozen and then re-whip until light and smooth. The frosting might break again when whipping, which is a not a problem. Just keep mixing and it will eventually come together just like the first time you mixed it.

Looking for More Frosting Recipes? Check these out!

This frosting is just one of many options featured in the best frosting recipes without powdered sugar.

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