Swiss meringue buttercream is a luxurious, silky frosting made by gently cooking egg whites and sugar, then whipping them into a glossy meringue before adding butter. Using 10 egg whites creates a large batch perfect for frosting multiple cakes or cupcakes with a light texture and stable finish that holds up well in warm conditions.
Ingredients
- 10 large egg whites (about 330g)
- 500g granulated sugar (2 1/2 cups)
- 680g unsalted butter, softened to room temperature (3 cups or 1 1/2 pounds)
- 1 tablespoon pure vanilla extract
- 1/4 teaspoon salt (optional, enhances flavor)
Instructions
- Prepare your equipment: Ensure your mixing bowl and whisk attachment are completely clean and dry. Any grease or moisture can prevent the egg whites from whipping properly.
- Combine egg whites and sugar: In a heatproof mixing bowl (preferably stainless steel or glass), whisk together the egg whites and granulated sugar until combined.
- Cook over simmering water: Place the bowl over a double boiler or a pot of simmering water, making sure the bottom of the bowl does not touch the water. Whisk constantly until the sugar dissolves and the mixture reaches 160°F (71°C) on a candy thermometer. This step is critical for food safety and to ensure the sugar is fully dissolved.
- Whip the meringue: Remove the bowl from heat. Using a stand mixer fitted with the whisk attachment, beat the egg white mixture on medium-high speed until stiff, glossy peaks form and the bowl feels cool to the touch (about 8-10 minutes). This can take longer with large batches—do not rush.
- Add butter gradually: With the mixer on medium speed, add the softened butter a few tablespoons at a time. Incorporate each addition fully before adding more. The mixture may look curdled or soupy at times; keep beating and it will come together into a smooth, creamy buttercream.
- Flavor and finish: Once all the butter is incorporated, mix in vanilla extract and salt (if using). Continue beating until the buttercream is smooth and spreadable. If the buttercream is too soft, chill for 10-15 minutes and then rewhip.
- Use or store: Use immediately to frost cakes or cupcakes, or store as directed below.
Tips
- Egg white substitution: Use pasteurized egg whites if you’re concerned about raw eggs or food safety. They work well in this recipe without cooking.
- Butter temperature: Butter should be softened but still cool, around 65-70°F (18-21°C). Too warm and the buttercream will be runny; too cold and it won’t incorporate smoothly.
- Fix curdled buttercream: If the mixture looks broken or soupy, chill it briefly and then beat again. Sometimes warming your bowl slightly helps, but avoid overheating.
- Storage: Swiss meringue buttercream can be stored covered at room temperature for up to 1 day, refrigerated for up to 5 days, or frozen for up to 3 months.
Serving Suggestions
This Swiss meringue buttercream is perfect for frosting layered cakes, cupcakes, or cookies. Its light texture pairs beautifully with flavors like vanilla, chocolate, lemon, or berry. For a classic look, pipe rosettes or smooth it over cakes with an offset spatula. Because it holds its shape well, it’s great for intricate piping designs and wedding cakes.
Variations
- Chocolate Swiss Meringue Buttercream: Add 100-150g melted and cooled dark chocolate after the butter is incorporated for a rich chocolate frosting.
- Fruit-flavored: Replace vanilla with 2-3 tablespoons of fruit puree or fruit extracts like raspberry, lemon, or passion fruit for a fresh twist. Add after butter is fully mixed.
- Coffee or mocha: Dissolve 1 tablespoon instant espresso powder in 1 tablespoon hot water and add with vanilla for a coffee-flavored buttercream.
- Almond or other nut flavors: Substitute vanilla with almond extract or add finely ground toasted nuts for texture and aroma.
Storage and Reheating
Room temperature: Swiss meringue buttercream can be safely left out at room temperature for up to 24 hours if your kitchen is cool (below 70°F/21°C). Cover it tightly with plastic wrap to prevent drying.
Refrigeration: Store in an airtight container in the fridge for up to 5 days. Before using, let it come to room temperature for about 30-60 minutes, then rewhip with a mixer to restore its silky texture.
Freezing: Freeze buttercream in an airtight container for up to 3 months. Thaw overnight in the refrigerator, then bring to room temperature and rewhip before use.
Reheating tips: If the buttercream appears grainy or separated after storage, gently warm it in a warm water bath or microwave in short bursts (5-10 seconds), stirring in between, then rewhip. Avoid overheating as it can melt the butter and ruin texture.
Frequently Asked Questions
1. Can I use regular granulated sugar or do I need superfine sugar?
Regular granulated sugar works fine, especially as it dissolves during the cooking step. Superfine sugar dissolves faster, but it’s not essential if you whisk constantly while heating.
2. Why is my Swiss meringue buttercream grainy?
Graininess usually means the sugar hasn’t fully dissolved or the butter was too cold or added too quickly. Make sure to cook the egg whites and sugar to 160°F and add softened butter gradually while mixing.
3. What do I do if my buttercream splits or curdles?
If the buttercream looks broken or soupy, chill it briefly and then beat it again at medium speed. If needed, warm the bowl slightly to help it come back together, but avoid overheating.
4. Can I make Swiss meringue buttercream ahead of time?
Yes, it can be made up to 5 days ahead and stored in the fridge. Bring it back to room temperature and rewhip before using. It also freezes well for longer storage.
5. Is Swiss meringue buttercream safe to eat raw?
The egg whites are gently cooked to 160°F, which is the USDA recommended temperature to make them safe by eliminating salmonella risk. Do not skip this step.
6. Can I add food coloring to this buttercream?
Yes, gel or paste food coloring works best as it won’t thin the buttercream. Add color after the butter is fully incorporated and mix well.
Swiss meringue buttercream made with 10 egg whites yields a large quantity of smooth, stable frosting ideal for decorating large cakes or many cupcakes. Its light texture and delicious flavor make it a favorite among bakers for both everyday and special occasion desserts.
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