clock clock iconcutlery cutlery iconflag flag iconfolder folder iconinstagram instagram iconpinterest pinterest iconfacebook facebook iconprint print iconsquares squares iconheart heart iconheart solid heart solid icon
yellow cupcakes and chocolate mousse buttercream

chocolate mousse buttercream frosting

5 Stars 4 Stars 3 Stars 2 Stars 1 Star

No reviews

  • Author: Sepideh Esmaili Campos
  • Total Time: 45 minutes


A silky smooth chocolate buttercream that pairs well with yellow and chocolate cake!


  • 2 sticks unsalted butter (1 cup), cold
  • 6 ounces dark chocolate (72% cocoa), chopped
  • 2 egg whites
  • 1 egg
  • ¾ cup granulated sugar
  • 1 tablespoon cocoa powder
  • ½ teaspoon sea salt
  • 1 teaspoon Vanilla


  1. Unwrap the butter and place between two sheets of plastic wrap. Use a rolling pin to pound the butter into a ¼ inch thick rectangle between the plastic. Place the butter in the refrigerator.
  2. Place the chocolate in a large bowl. Pour an inch of water in a small pot (use a pot that allows the chocolate bowl to easily fit on top without the bottom of the bowl touching the water). Bring the water to a boil over high heat, lower to a simmer, place the bowl of chocolate on top of the simmering water.
  3. Stir the chocolate until it is fully melted, 5-8 minutes. Remove the bowl of chocolate from the heat and set aside to cool, but not harden, at room temperature.
  4. Add more water to the pot if it has mostly evaporated. Bring the water back up to a boil and lower to a simmer.
  5. Combine the egg whites, egg, sugar, and cocoa powder in the bowl of a standing mixer.
  6. Place the bowl of eggs and sugar on top of the pot with simmering water. Whisk and heat the eggs until the sugar dissolves, the mixture becomes thick and glossy, and the temperature registers between 120-140 degrees Fahrenheit, about 8-10 minutes.
  7. Move the bowl of warm eggs to a standing mixer and, with the whisk attachment in place, whisk on medium speed until the eggs are thick and have tripled in volume and the bowl is completely cool to the touch, 10-15 minutes. The eggs should be completely cooled so that the butter doesn’t melt.
  8. Add the salt and vanilla to the eggs and whip to incorporate.
  9. With the mixer running on medium-low speed, add the butter one small piece at a time. Wait until the butter is incorporated before adding the next piece of butter.
  10. At any point your frosting might look liquidy or curdled, don’t panic. Just keep adding the butter and mixing. When the last of the butter has been added, continue to whisk on medium speed until the frosting is smooth and glossy.
  11. Add the cooled, melted chocolate to the buttercream a third at a time, whisking well in between additions.
  12. Chill the frosting in the refrigerator until you’re ready to frost your cake or cupcakes.
  • Prep Time: 30
  • Cook Time: 15


  • Serving Size: enough to generously pipe 12 cupcakes or moderately spread over 24 cupcakes