This Swiss Meringue Buttercream is one of those recipes that separates casual bakers from precision-driven ones. It’s a true professional frosting—silky, refined, and less sweet than American buttercream, with a texture that melts on the tongue. It’s the kind of buttercream you’d expect on a perfect bakery cupcake or wedding cake.

That said, it’s not a “wing-it” recipe. This is a technical buttercream that relies entirely on temperature control. Without a thermometer, the chances of success are slim. The steps look simple, but every one of them depends on precision. If you skip the temperature checks, you’ll end up with a soupy mess instead of the smooth, satin finish that makes Swiss meringue so special.

When done properly, this buttercream is bulletproof—it’s smooth, light, stable at room temperature, and pipes beautifully. The optional white chocolate addition adds a subtle sweetness and extra gloss that makes the frosting easier to work with, especially for beginners.

Storage and Stability
This buttercream keeps in the refrigerator for up to 7 days or in the freezer for up to 2 months. Always bring it back to room temperature before re-whipping. If it appears split after chilling, beat on medium speed until it smooths out again.

Results
White Chocolate Swiss Meringue Buttercream is smooth, velvety, and pleasantly sweet without being cloying. It’s stable enough for piping and layer cakes yet light enough to melt on the tongue. This recipe demands patience and a thermometer, but the payoff is bakery-level frosting you can rely on every single time.

Swiss Meringue Buttercream

Recipe by Ellen

Servings

servings

Prep time

minutes

Cooking time

minutes

Calories

300

kcal

Ingredients

5 large egg whites (150 g)
1 ½ to 1 ⅔ cups (300 to 330 g) granulated sugar (or toasted sugar for more caramel depth) — use 300 g for classic balance, up to 330 g for a touch more sweetness
Heaping ¼ teaspoon fine sea salt
2 cups (450 g) unsalted butter, cool and pliable (18–20 °C / 65–68 °F), not shiny or soft
1 teaspoon pure vanilla extract + ½ scraped vanilla bean —or 2 teaspoons vanilla paste for depth
Optional: 1 ½ to 2 oz (40–60 g) white chocolate, melted and cooled to 28–30 °C (82–86 °F); adds gloss and slight sweetness

Directions

Heat, Dissolve, Pasteurize
Combine egg whites, sugar, and salt in the mixer bowl.
Place the bowl over barely simmering water (bowl bottom not touching).
Whisk gently but constantly — you’re keeping the mixture moving, not whipping air in.
Heat until:
Temperature reaches 74–78 °C (165–172 °F)
Mixture feels completely smooth when rubbed between fingers (no grit).
This typically takes 6–10 min, but can vary depending on:
Heat intensity
Bowl thickness
Kitchen temperature
Do not proceed until the sugar is fully dissolved.
Even if you reach 165 °F, if it still feels gritty, keep whisking until smooth.
Whip to Cool, Stiff Meringue
Move bowl to mixer fitted with whisk attachment.
Beat on medium-high (speed 6–8) until:
Stiff, glossy peaks form, and
Bowl feels neutral or slightly cool to touch (about 24–28 °C / 75–82 °F).
Typical time: 8–20 min, depending on conditions.
If you overheated your eggs closer to 170 °F or have a warm kitchen, expect this cooling to take 30–60 min total (mixing + intermittent chilling). That’s normal.
Cooling Hacks (if it won’t drop below 30 °C)
Stop mixer for a few minutes to release trapped heat.
Rest the bowl on frozen peas, ice packs, or a bag of frozen corn for 2–5 min, rotating the bowl occasionally.
Never over-chill; you want evenly cool, not cold edges.
If the meringue feels only faintly warm but reads 30 °C, you can proceed — thermometers often read high in foams.
Add Butter (Emulsify)
Ensure butter is 18–20 °C (65–68 °F) — soft but not glossy.
Switch mixer to medium speed (4–5).
Add butter one cube every 10 seconds, allowing each to blend before the next.
The mixture may appear:
Soupy if meringue is warm,
Curdled if meringue is cool — both are normal.
Keep beating; it will come together.
Once all butter is in, mix 2–3 min more until smooth.
If it stays soupy: refrigerate 5 min, then beat again.
If it looks curdled: warm bowl sides with your hands or a warm towel 5–10 sec, then beat again.
Flavor & Finish
Add vanilla (and melted white chocolate if using, at 28–30 °C).
Beat on medium until incorporated.
Switch to paddle and run on low for 30–60 sec to knock out air bubbles. Enjoy!

Notes

Storage
Room temp (≤21 °C): up to 6 h.
Fridge: 1 week, airtight.
Freezer: 2 months, well sealed.
Thaw overnight in fridge.
Bring to 18–20 °C and re-whip: whisk 30 s, paddle 30 s low speed.