Custards, creams & meringues
Swiss Meringue Buttercream
Beurre suisse à la meringue · A stable emulsified buttercream made by whipping egg whites and granulated sugar over a water bath until the sugar fully dissolves and the mixture reaches 70°C/160°F, then whipping to a stiff glossy meringue before gradually incorporating soft room-temperature butter. The result is a silky, satin-textured frosting that pipes cleanly and tastes less sweet than American buttercream.
The formula
egg white : sugar : butter = 1 : 1 : 1.5 by weight (e.g. 150 g egg white : 150 g sugar : 225 g butter)
At this ratio the buttercream holds firm piping lines and has enough structural integrity to fill a cake. Raising sugar to 180 g yields a slightly stiffer, more stable result ideal for hot climates.
Identity
- Egg whites and sugar must reach exactly 70°C/160°F before whipping — this dissolves sugar completely and pasteurizes the foam
- The meringue must be whipped to stiff, glossy, billowing peaks before any butter is added
- Butter must be 18–21°C (65–70°F) — soft enough to ribbon, cold enough not to melt the foam
- Butter is incorporated gradually once the meringue has cooled to roughly the same temperature
- The finished cream is beaten with the paddle at medium speed after all butter is added to develop a smooth, dense satin texture
Ingredients
| Base | Egg whites, large (~30 g each; 150 g ≈ 5 whites) | Pasteurization by heat is intrinsic to the Swiss method. Use pasteurized whites if serving to at-risk populations. |
| Base | Granulated sugar | Must fully dissolve in the whites over heat. The dissolution point of sucrose is 112°C/234°F but in the water phase of egg whites it completes at 70°C. |
| Fat | Unsalted butter, 82% fat minimum | European-style butter preferred for higher fat content and lower water. American 80% butter works but may yield a slightly softer result. |
| Seasoning | Vanilla extract (optional) | Classic seasoning; add 1–2 tsp after butter is fully incorporated. |
| Binder | Cream of tartar, pinch (optional) | Adds marginal stability to the meringue foam and brightens flavor. Use 1/8 tsp per 150 g egg white. |
Method
- 1Combine egg whites and sugar in a clean, grease-free bowl. Set over a saucepan of barely simmering water (the bowl must not touch the water).Gentle indirect heat dissolves the sugar in the egg-white moisture without cooking the proteins prematurely. Direct heat risks scrambled whites.
- 2Stir constantly with a whisk or heatproof spatula until the mixture reaches exactly 70°C/160°F on a calibrated probe thermometer.70°C is the minimum pasteurization temperature and the point at which sucrose is fully dissolved in the egg-white liquid. Below this, undissolved sugar crystals cause grittiness. Above 82°C, egg proteins begin to coagulate irreversibly.
- 3Transfer the bowl to a stand mixer and whip on high speed with the whisk attachment until the meringue is glossy, holds stiff peaks, and has cooled to room temperature or just below (roughly 21–24°C). This takes 8–15 minutes depending on batch size.Whipping incorporates air into the protein matrix, creating the foam that will eventually be stabilized by the fat phase. The meringue must be cool before butter addition — warm butter melts the air bubbles; cold butter causes the fat to seize before emulsification.
- 4Switch to the paddle attachment. With mixer running on medium speed, add softened butter one tablespoon at a time, waiting briefly between each addition until fully incorporated before adding the next.Gradual incorporation allows each butter droplet to coat the air cells of the meringue before the next arrives. Adding too fast traps unmelted butter in discrete pockets, causing a broken, lumpy texture.
- 5Once all butter is added and the mixture appears cohesive, continue beating on medium-high for 2–3 minutes until the cream is smooth, dense, and satin in texture. Add vanilla or other flavoring now; beat briefly to incorporate.Extended beating with the paddle collapses oversized air bubbles and aligns fat crystals, developing the characteristic smooth, sliceable consistency. The cream should pull cleanly from the paddle.
Techniques that matter
Double-boiler dissolution
The water-bath method provides controlled, even heat that dissolves sugar without risk of scorching or prematurely setting egg proteins. It is the defining structural step of Swiss vs. Italian buttercream.
Stiff-peak meringue formation
The meringue must reach full stiff peaks to provide an aerated protein network capable of holding the fat phase in suspension. Under-whipped meringue lacks structural integrity and collapses when butter is added.
Temperature-matched emulsification
Both the meringue and the butter must be within a narrow temperature band (18–24°C) for the fat-in-air emulsion to form cleanly. This is the most technically demanding step and the primary source of failure.
Paddle homogenization
Switching to the paddle after butter incorporation breaks down large air bubbles and develops a tight, smooth grain — the hallmark of professional Swiss buttercream texture.
Variations & derivatives
Chocolate Swiss Buttercreamuniversal
Melt 170 g good-quality dark chocolate (70% cocoa), cool to 32°C, and fold in after the buttercream is complete. Alternatively, whisk 45 g cocoa powder with a small amount of warm cream into a paste before folding in.
Caramel Swiss Buttercreamuniversal
Replace up to 30% of the sugar with light brown sugar for a subtle caramel note, or fold 100–150 g room-temperature caramel sauce into the finished buttercream.
Coffee Swiss Buttercreamuniversal
Dissolve 2 tbsp instant espresso powder in 1 tsp hot water, cool, and add with vanilla. Or infuse the buttercream with 1 tbsp finely ground coffee in a cheesecloth pendant during whipping.
Fruited Buttercreamuniversal
Reduce 120 g fruit purée to 60 g over medium heat, cool completely, and fold into finished buttercream. Raspberry, passion fruit, and mango work particularly well.
Swiss Buttercream with MascarponeItaly/pan-Atlantic
Substitute 25–30% of the butter weight with room-temperature mascarpone for a slightly tangier, creamier result. Do not exceed 30% or the cream will lose its pipeability.
Used in these dishes
Substitutions
- Granulated sugar → Caster sugar — Caster dissolves marginally faster over heat but the result is virtually identical. Do not use powdered sugar — its cornstarch content will affect texture and dissolution.
- European butter (82%+ fat) → American butter (80% fat) — Acceptable; the slightly higher water content may yield a softer cream, especially in warm conditions. Reduce water further by using 5–10% less butter or adding 1 tbsp cornstarch per batch.
- Egg whites → Liquid whole egg (not whites only) — Substituting whole egg changes the fat-to-protein ratio and produces a richer but less stable cream closer to French buttercream. Not a 1:1 swap; start with half the volume.changes result
- Butter → Vegan butter (high-fat, 80%) — Some brands work acceptably; many contain water or oils that destabilize the emulsion. Test on a small batch first. Do not use spreadable tub margarines.changes result
Troubleshooting
The buttercream turns grainy, curdled, or soupy when butter is added
Temperature mismatch: the butter is too cold (below 16°C) and the fat seizes before emulsifying, or the meringue is still warm and melts the butter droplets. → Set the mixing bowl over a shallow pan of warm water (40°C maximum) for 20–30 seconds, then re-whip on medium speed. Alternatively, let the butter come to precisely 20°C on its own and restart. Continue until the emulsion stabilizes — it will.
The finished buttercream is too soft and won't hold peaks
Too much liquid in the butter (American butter), or the butter was too warm when added, partially melting the meringue foam. → Refrigerate the bowl for 15 minutes, then re-whip with the paddle on medium-high for 2–3 minutes. If still soft, add 1–2 tbsp butter at a time with re-whipping. In hot weather, add 30 g sifted powdered sugar per 450 g batch for firmness.
The buttercream is gritty or sandy in texture
The sugar was not fully dissolved before whipping began — either the mixture was removed from heat below 70°C or the cook did not stir adequately during heating. → Dissolve remaining crystals by setting the bowl over simmering water and whisking until the thermometer reads 70°C again, then re-whip. Prevention is primary — always use a thermometer.
The buttercream weeps or weeps at the seams of a cake after sitting overnight
The emulsion broke during mixing (usually from overbeating warm butter or temperature cycling), or insufficient sugar relative to butter. → Re-whip the entire batch with the paddle on medium-high speed for 3–4 minutes. If weeping persists, it indicates insufficient sugar or fat ratio; add 15 g more powdered sugar and re-whip. Refrigerate the finished cake to resolidify the butter phase.