chocolate mousse buttercream frosting

chocolate mousse buttercream frosting

This chocolate mousse buttercream frosting is smooth, delicately sweetened, and full of chocolate flavor. It pairs perfectly with both yellow and chocolate cake and it’s a huge hit with my family.

One of the biggest blessings in me and Kenny’s marriage is how much we love each others’ family. Kenny’s cousin graduated from High School this weekend and we were lucky enough to help him celebrate. Watching our cousin accept his diploma and multiple awards for leadership was so inspiring and we couldn’t be more proud of him. I baked cupcakes for the graduation party which included a delicious menu of lasagna, garlic bread, and Caesar salad. As my Aunt joked, we were totally “carbo loading” so I wanted to keep the chocolate frosting light and airy.

I baked yellow and chocolate cupcakes, which I normally like to pair with this chocolate ganache frosting. To balance the carb heavy meal I sought out a light chocolate buttercream. After much experimentation I developed a recipe that mimics Swiss meringue buttercream by whipping eggs and sugar until tripled in volume. Traditional Swiss meringue buttercream uses only egg whites but I added an egg yolk for a silky, rich texture. When paired with my yellow cupcakes you use two egg yolks for the cake and save the two egg whites for this frosting so nothing goes to waste!

In my attempt to make all of my recipes a little healthier, I experimented with different techniques to use less butter. By whipping the frosting longer than normal and using chocolate with a high percentage of cocoa, I was able to achieve the right texture while removing an entire stick of butter from the recipe.

With the right tools and some patience, this recipe will become your favorite light chocolate frosting! Enjoy.

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yellow cupcakes and chocolate mousse buttercream

chocolate mousse buttercream frosting

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  • 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

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