All you need are 5 ingredients to make a creamy and silky smooth Swiss Meringue Buttercream. It is perfect for decorating, piping, or spreading over baked goods.
Place the bowl over a pan of simmering water. Make sure the water does not touch the bowl.
Whisk the egg whites occasionally while it warms up. When the mixture has warmed, whisk it constantly. You will heat the mixture until it reaches an internal temperature of 160ºF or until it's not grainy between your fingers.
Transfer the bowl to a stand mixer, mix with a whisk attachment until you get room temperature glossy peaks.
Switch to a paddle attachment and while the mixture is running on low, add tablespoon sized dollops of room temperature butter making sure to let the butter incorporate before you add the next piece.
Once all the butter is incorporated, go ahead and add the vanilla extract. You can transfer it to a piping bag or to a ziplock bag to store in the refrigerator or freezer.
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Notes
It is essential to have a clean and dry bowl for whipping the egg whites. The egg whites cannot contain any egg yolk as well. If the bowl is not completely clean or yolk-free, it prevents your meringue from setting up.
If your equipment or bowl has grease on it, wipe down everything with lemon juice or vinegar.
Eggs are easier to separate when cold, but egg whites whip up easier when closer to room temperature. I recommend separating them in advance if you have the time. In addition, allowing the egg whites to sit gives them a chance to relax, which improves their elasticity during the whipping process.
It is entirely normal for the SMBC to look soupy or curdled after adding the butter. Not to worry, just continue to let it whip, and it’ll come together at the end.
If the mixture does not come together and stays curdled after 5 to 10 minutes, you can place the mixing bowl over a simmering pot to let the edges of the meringue warm up before continuing to mix it.
Keep in mind that, like all buttercream, this recipe uses butter. This means if it is humid or hot, the buttercream will melt.
If your mixer’s motor is starting to overheat, you can give the mixer a break by placing the whisk or paddle attachment in the mixing bowl and placing everything into the fridge for 20 to 30 minutes.