Swiss Meringue Buttercream
This is the workhorse of professional cake finishing. By cooking the whites, you create a sterile, silky base that holds its shape under pressure and pipes with absolute precision.
Temperature is your only enemy
Your butter must be soft—yielding to a light thumb press—but not greasy. If the butter is too cold, the emulsion breaks; too warm, and it turns into a soupy puddle.
- Stand mixer with whisk attachment
- Heat-proof bowl
- Saucepan (for water bath)
- Digital instant-read thermometer
- Silicone spatula
What goes in.
- 5 largeegg whites, room temperature
- 1 1/2 cupsgranulated sugar
- 2 cupsunsalted butter, cubed and softened
- 1 tspvanilla bean paste or extract
- 1 pinchfine sea salt
Dissolving the Sugar
Whisk the whites and sugar over simmering water until the mixture reaches 160°F. Rub a drop between your fingers; if you feel a single grain of sugar, keep heating.
The method.
Heat the base
Place the egg whites and sugar in a bowl over a saucepan of barely simmering water. Whisk constantly until the sugar is fully dissolved and the mixture reaches 160°F.
Whip the meringue
Transfer to the stand mixer. Whisk on medium-high speed until stiff, glossy peaks form and the bowl feels cool to the touch, about 8 to 10 minutes.
Mount the butter
Turn the speed to low. Add the butter one tablespoon at a time. Do not rush; wait for each piece to incorporate before adding the next.
Emulsify
The mixture may look curdled halfway through—keep going. Once all butter is in, switch to the paddle attachment and beat on medium-low until the texture is uniform and silky.
Other turns to take.
Chocolate
Add 6 ounces of melted, cooled semi-sweet chocolate during the final step of beating.
Fruit
Fold in 3 tablespoons of reduced fruit puree or freeze-dried fruit powder once the emulsion is complete.
When it doesn't go to plan.
Wipe your mixing bowl with a paper towel dipped in vinegar to ensure there is zero fat residue, which prevents meringue from rising.
If the buttercream looks like scrambled eggs, the butter was likely too cold; briefly warm the bowl with a kitchen torch or hair dryer and keep beating.
If the mixture is too soft or soupy, refrigerate the entire bowl for 15 minutes, then beat again.
The ones that keep coming up.
Can I make this ahead?
Yes. It keeps in the refrigerator for one week or the freezer for three months. Bring it back to room temperature and re-whip until smooth before using.
Why did my frosting turn yellow?
Usually, this happens if the butter was too warm when added, or if you used a very high-fat, deep yellow butter. It does not affect the outcome.