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Everyone loves Swiss meringue buttercream because it is so quick and easy to make. This frosting is based on an ingredient we all have in the kitchen – egg whites, cooked in a water bath and whipped until light and airy. The final touch is given with the addition of butter which turns the mixture into a smooth frosting.

Not to mention how versatile this silky frosting is! You can add anything that comes to mind – chocolate chips or melted chocolate, peanut butter, fresh or dried fruits, vanilla paste or vanilla beans… You just can’t go wrong with Swiss meringue buttercream!

Why You Should Not Omit Cream of Tartar in Your Swiss Meringue Buttercream Recipe


However, even the simplest recipes can fail. In the case of Swiss meringue buttercream, there is a number of things that can go wrong. For one, we tend to underestimate the importance of cream of tartar and often omit it.

Why is cream of tartar so important in meringues? Well, cream of tartar contains acid which produces more stable meringues that are less likely to weep. Furthermore, the acidity of cream of tartar also makes a great balance with the simple sweetness of this frosting. Luckily, if you don’t have cream of tartar in your pantry, you can easily replace it with another acidic ingredient like lemon juice or white vinegar. Add 1/8 teaspoon cream of tartar per egg white in the recipe, or replace with a ½ teaspoon of lemon juice or white vinegar per egg white before beating.

I consider investing in cream of tartar a very wise decision firstly, because it has an indefinite shelf life and secondly, because cream of tartar substitutes not always produce exactly similar final products. Last but not the least, cream of tartar is not limited to meringues; it can be used to improve a great number of dishes.

Besides Omitting Cream of Tartar, What Other Mistakes Can Ruin Your Swiss Meringue Buttercream?


The other two common mistakes when making Swiss meringue is not adding enough sugar and not cooking it at high enough heat. One, or a combination of these two, results in an eggy-flavored mixture. The addition of butter will only make it worse; the mixture will become thick and greasy.


When it comes to sugar, you can use the granulated version when you’re making a meringue, but many pro cooks usually opt for caster sugar because it dissolves more easily.  How much sugar do you add to your Swiss meringue? Soft meringues usually need 2 tablespoons of sugar for every egg white; however, Swiss meringue belongs to the group of hard meringues which call for a ¼ cup per egg white, and usually contain an acidic substance like cream of tartar or lemon juice.

Increasing the amount of sugar also ensures that the sweetness and flavor of the meringue are not overpowered by the butter and result in a lighter final product. The very increase of sugar requires the meringue to be cooked to a higher temperature.


Meringues and heat are in a serious relationship! Meringues hate low cooking temperatures and humidity, so much so you must always make sure the kitchenware you’re using is completely dry. You are even advised to avoid making meringues on humid days!

Swiss meringue is made with cream of tartar or another acid, sugar, and egg whites, by heating them in a double boiler over boiling water. Whisk egg whites and sugar just to break up the whites, but not so hard that they form a foam. The sugar will melt and prevent the egg whites from coagulating. Heat over medium-high heat and whisk constantly until the temperature of the egg whites reaches 120 to 185 degrees F or higher (use a digital thermometer to check). Remove the bowl from the heat, and keep beating the warm whites until stiff peaks are formed. The temperature at this point should be 90 degrees F.

This is important because the meringue mixture and the butter which is to be added need to have similar temperatures (the butter should be softened to about 65 degrees F before being added to the meringue). If their temperatures are too different, the resulting buttercream will be either too thick and greasy or too thin and runny.

Swiss Meringue Buttercream with Cream of Tartar Recipe



  • egg whites from 5-6 large eggs (2/3 cup)
  • 1 2/3 cup caster sugar
  • 1/4 teaspoon cream of tartar
  • 1/2 teaspoon salt
  • 5 sticks unsalted butter, softened
  • 2 teaspoons vanilla extract (optional)

Method of Preparation:

Step 1

Place a ring of foil at the bottom of a large pot (to prevent the bowl from touching the pot) and fill the pot with about 1 1/2 inches of water. Place over high heat until the water starts simmering.

Step 2

In a bowl, combine the egg whites, cream of tartar, sugar, vanilla extract, and salt. Set the mixture over the previously heated water, stirring and scraping constantly with a spatula for about 10-13 minutes, until the whites reach 185°F. Whip the mixture with an electric mixer at high speed for about 10-12 minutes, until the meringue has stiff peaks, and feels cool & smooth to touch.

Step 3

With the mixer still running, add the butter. Keep whipping until the mixture becomes thick, creamy, and soft.

Note: In case your buttercream still turns loose even after you have taken all these precautions, don’t throw it away! Place it in the refrigerator for about 15 minutes and whip again until it becomes thick. On the other hand, if the buttercream is too thick, set the bowl over a pan filled with hot water until it loosens up a bit, then whip again until it softens.

Storing Swiss Meringue Buttercream


Swiss buttercream is best when used immediately as a cake or cupcake frosting. If you want to store it, place it in a gallon-sized ziplock bag, seal and lay flat. It will keep for up to two weeks in the fridge or several months in the freezer. If stored for longer it won’t spoil but will absorb unpleasant odors.

When you’re ready to use the buttercream for frosting, take it out and warm to 72 degrees F, then whip in order to make it soft and spreadable.

Cakes other desserts frosted with Swiss meringue buttercream don’t need to be refrigerated. due to the fact that the buttercream is fully cooked. On the contrary, refrigerated cakes stale faster!

Enjoy your perfect Swiss meringue buttercream!

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