Ultra-smooth and light, chocolate Swiss meringue buttercream is not overly sweet and incredibly stable for frosting cakes, cupcakes and even macarons!
What is Swiss meringue buttercream?
Swiss meringue buttercream is a frosting made with Swiss meringue and butter.
Swiss meringue is made of egg whites and sugar cooked in a double-boiler (Bain Marie), then whipped into fluffy meringue.
How to make chocolate Swiss meringue buttercream:
While it’s not as easy as American buttercream, chocolate Swiss meringue buttercream is quite simple to make once you understand and follow simple rules of making a meringue.
I won’t go in-depth with meringue rules here, but I highly recommend reading my Meringue 101 post to learn more.
Step 1. Make meringue
- In a heat-proof bowl, combine sugar and egg whites together. And place the bowl over simmer water.
- Cook the egg whites gently until it reaches 160°F, whisking it continuously. (This’s my favorite thermometer!) You shouldn’t feel any sugar granules when you rub the mixture between your fingertips.
- Now remove from heat and whisk it until stiff peaks form. At this point, meringue should be completely cooled.
Make sure the bowl and whisks are completely grease free. It’s ideal to use stainless steel or glass bowl for making meringue.
Also, be careful when separating egg whites. You should have even smallest amount of yolk in the egg whites. Here’s why.
Step 2. Add butter
- Add room temperature butter, one tablespoon at a time, whisking the frosting thoroughly after each addition.
- Continue whisking the buttercream until all the butter is added and the frosting is super light and fluffy.
Room Temperature Butter
It’s important to use room temperature butter. When you push a finger into it, the butter should dent with some resistance.
If the buttercream tastes greasy and too buttery, it means it’s under-mixed. Keep whisking it. The properly mixed Swiss meringue should taste light and clean!
Step 3. Add melted chocolate
- Melt the chocolate and cool it to room temperature. (See the directions below.)
- Add cooled melted chocolate into the buttercream.
- Switch to paddle attachment and beat the frosting until well combined.
How to melt chocolate in a microwave:
- Chop dark chocolate bar into small pieces (or use chocolate chips, if desired) and place it in a microwave-safe bowl.
- Microwave it for 1 minute at 50% power (I use 1000watt microwave. If your microwave is higher power, you may need to reduce the power even more!)
- Stir the mixture and put it back for 30 seconds at 50% power.
- Stir it again and put it back for 15 seconds at 50% power. And repeat this step until all the chocolate is melted completely.
Troubleshooting common issues
For troubleshooting any issues, check out my complete tutorial on how to make Swiss meringue buttercream.
Chocolate Swiss Meringue Buttercream
- 6 egg whites (Note 1)
- 1 ½ cups (300g) granulated sugar
- ½ teaspoon coarse kosher salt
- 1 ½ cups (340g) unsalted butter at room temperature (Note 2)
- 8 oz semi-sweet chocolate (Note 3)
- In a small saucepan, bring a small amount of water to a boil. Reduce the heat to simmer.
- In medium heat-proof bowl (I used my stand mixer bowl), whisk together egg whites and sugar and place it over the saucepan with simmering water. (This is a make-shift double boiler. Make sure the bottom of the top bowl doesn't touch the water.)
- Cook the egg white mixture until sugar is completely melted and it reaches 160°F (70°C) stirring continuously, about 5 minutes. (This's my favorite thermometer!)
- Now, remove the bowl with egg white mixture from heat. Then whisk it on medium speed for a minute, then slowly increase the speed to medium high and beat until stiff peaks form and the mixture is cool to touch, about 10 minutes. (It may take longer with a hand-mixer.)
- Meanwhile, melt the chocolate in a microwave according to package directions. Let it cool.
- Once the meringue reached stiff peaks, scrape the side of the bowl with a spatula and add salt.
- Turn on the mixer on medium speed and start adding butter, one tablespoon at a time. Make sure the butter is fully incorporated before adding the next piece. (NOTE: It's normal if buttercream starts to curlde half way. Keep adding the butter!)
- Keep whisking the buttercream until smooth, light and fluffy, about 10 minutes.
- Now, switch to a paddle attachment and add cooled melted chocolate. Beat the buttercream until well combined, about a minute.
Tips & Notes:
Chocolate Swiss meringue buttercream can be made in advance and frozen for up to 3 months, or refrigerated for up to 2 weeks. Thaw frozen buttercream on the counter overnight. Whip it before using. Note 1: While I’ve had success with carton egg whites, not all brands work for meringue. But if you want to try, you’ll need 210g of liquid egg whites. Note 2: Make sure the butter isn’t too soft. When you push a finger into it, the butter should dent with some resistance. Note 3: You may use any kind of dark chocolate. Both chocolate bar and chocolate chips will work. Please read the post above for microwave melting directions.