Italian Meringue Buttercream is silky smooth, creamy, & gorgeous. Here’s how to make the perfect buttercream for cakes and cupcakes.
*Metric measurements in the Notes.
- Combine the water and 1¼ cup sugar in a small saucepan and stir once or twice just to moisten the sugar. Do not stir again; stirring encourages the sugar to crystalize. Bring to a boil over medium high heat and continue to cook until it reaches a temperature between 248 and 250 degrees.
- As soon as you set the syrup to cook, begin the meringue. Beat the egg whites in a standing mixer fitted with the whisk attachment at medium speed until frothy. While beating, sprinkle in the cream of tartar and then the remaining ⅓ cup sugar. Beat until stiff, but not dry, peaks form. *The goal is to have the syrup at the right temperature and the meringue at the stiff peak stage at the same time. If the syrup is not quite ready, but the meringue is, continue to beat the egg whites with the mixer on the lowest speed until the syrup reaches the desired temperature. If the syrup is done before the meringue is ready, add a very small amount of hot (not cold) water to lower the temperature slightly.
- When the syrup is ready, turn off the mixer and quickly pour about ⅓ cup into the meringue. Immediately turn the mixer to medium-high and then continue to pour the hot syrup into the meringue in a thin, steady stream. Try to keep the syrup from getting on the beater, although some will get on there no matter what you do.
- Continue to beat the meringue with the whisk attachment at medium speed, until you touch the bottom of the bowl and it is cool to the touch. *It’s important to not add the butter before the meringue is completely cool, so that the butter doesn’t melt.
- With the mixer running at medium speed, add 2 or 3 tablespoons of the butter at a time. Beat until each addition of the butter is incorporate before adding more. Keep mixing and adding the butter bit by bit until all 6 sticks are incorporated. If the buttercream doesn’t look completely smooth at this point, just keep beating. It will smooth out. If it looks runny or curdled, the butter has probably melted. Put it in the refrigerator for 20 or 30 minutes and then continue beating until it’s smooth. (*See trouble shooting tips above the recipe in the post.)
- After the butter has been fully incorporated, you can add any flavor additions you like. (See the list of ideas right above the recipe.) At this point the buttercream is ready to use. If you’d like to store it for future use, see the notes below.
One reader was kind enough to leave the metric conversion for this recipe in a comment. Here’s what those measurements are: Butter: 1 lb 8 oz (1.5 lbs) = 680 grams; Sugar: 1.25 cups = 265 grams; Water: 1/2 cup = 105 grams (I tared the scale to zero and then added the water to get the weight in grams.)
You can refrigerate Italian Meringue Buttercream for up to a week or freeze it for up to two months. To reconstitute cold buttercream, it’s important to bring it to room temperature gently so that you don’t melt the butter. The simplest way to do this is to let it sit out on the counter until it reaches room temperature.
If you don’t have time for that, you can heat it in the microwave, on very low power, in 20 second spurts, checking for softness, breaking apart and stirring the buttercream as it begins to soften up. You can also place the buttercream over a pan of gently boiling water. If you select this method, break apart and stir the buttercream consistently as it warms to ensure that the buttercream on the bottom does not overheat.
You can also use a hairdryer, blowing warm air on the sides of the bowl and across the top of the buttercream to soften. As with the other two methods, break apart and stir the buttercream together as it warms. Whichever way you bring the buttercream to room temperature, beat it for a few minutes once it’s softened in your standing mixer fitted with the whisk attachment until it is smooth and creamy.
It’s better to have the buttercream a bit too cold when you begin beating it than too warm. Beating will continue to soften buttercream that is still a bit too cold. If it gets too warm, place back in the refrigerator for a bit.
Keywords: buttercream, Italian meringue, frosting, cake, cake decoration