Would you just look at that gorgeous chocolate cake filled with decadent chocolate mousse? Not to mention the chocolate buttercream and chocolate shavings that wrap around the entire cake. This cake seems simple in flavor, but really has the most memorable texture around. I knew right after I made my White Chocolate Mousse Cake, I needed to have a chocolate-chocolate version asap!

ALL THE CHOCOLATE THINGS

I know we have a lot of chocolate going on here, and that’s just what I wanted with this cake. Sometimes I come up with really crazy cake flavor ideas, and those are really fun for me to create. However, sometimes you just need a solid chocolate cake that you know will wow even your most diehard chocolate cake lover. Don’t be fooled by “oh this is just another chocolate cake.” Trust me when I say that adding the mousse filling really transforms this cake into something exquisite.

And when I say decadent – I mean it! There are so many different textures here that make this cake truly something special.

Make it Six

We have my rich tender chocolate cake layers as our base. For the 6 layers, I baked up three 6″ cake rounds, then sliced them in half to create six thin layers. This is most easily done when the cake is chilled (and mostly frozen in my opinion). If you want to keep the cake three layers, that’s totally fine. But be warned, after you try this chocolate mousse, you’re going to want more of it in every cake bite – the more layers mean the more you get of that decadent filling.

MOUSSE MAGIC

Again, we’re back with another mousse recipe (have you checked out my white chocolate mousse yet?). This time, I went for all the chocolate. Using semi-sweet chocolate was the right choice with this recipe, because there’s already a lot of sweet happening with the cake layers and buttercream. The mousse recipe is actually the exact same as my white chocolate mousse – we just switched up the chocolate. The result was the most airy fluffy mousse filling you’ll ever try.

And don’t let the mousse intimidate you! It doesn’t require any eggs, or anything that’s too difficult. Just make sure to let the cream cheese and chocolate cool a little before whipping them up together. We want smooth and airy mousse – no chocolate bits here!

Chocolate Buttercream

As for the chocolate buttercream, it’s a mixture of two of my favorite chocolate buttercream recipes – one where I only use cocoa (tastes like brownie batter), and one where I use mostly chocolate ganache to give the buttercream all that creamy chocolate flavor. This one uses BOTH techniques, and I love how it turned out. You can certainly use a darker chocolate in the buttercream if you prefer, too.

I mean, would ‘ya just look at that gorgeous cake slice?? You can SEE all the gorgeous texture this cake has to offer, and trust me, it’s simply irresistible.

Keep it simple

I was trying to figure out how to let this cake flavor speak for itself without too much of a trendy decoration style on the outside. To remedy that, I went with a classic look using chocolate curls (you can make your own or buy them at your local baking store). If you can’t find them, you can certainly use mini chocolate chips, chocolate jimmies/sprinkles, or even chop up a chocolate bar into small shards/pieces to add to the sides.

As for the top, I opted for a little bit of dusted cocoa. It’s bitter on it’s own, but with the cake it works beautifully! I love the look quite a bit. It was a good contrast to everything else that was happening around the rest of the cake.

clean slices

Now, for that gorgeous clean slice, I always recommend using a hot sharp knife (an ACTUALLY sharp knife makes all the difference), and slicing your cake while it’s cold. The mousse will become more and more soft and fluffy as it comes back to room temperature. The taste is everything with this stunning cake.

That’s it! As always, I hope you enjoy this new cake here for you, and that you tag me @bakinwithblondie or #bakingwithblondie on Instagram so I can join in on all the fun.

Happy Baking!

xo, Mandy

Get the Recipe: Chocolate Mousse Cake

Rich Chocolate Cake Layers, frosted with the best chocolate buttercream, covered in chocolate curls and filled with the most incredible fluffy chocolate mousse.
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Ingredients
 

Rich Chocolate Cake

  • 3/4 cup buttermilk , room temperature
  • 2/3 cup sour cream , room temperature
  • 3 whole large eggs, room temperature
  • 1 egg white , room temperature
  • 1 Tablespoon vanilla
  • 1/3 cup vegetable oil
  • 1/4 cup cocoa powder
  • 1/4 cup all purpose flour
  • 1 15.25oz (or similar) Chocolate Cake Mix (can be Devils food or Dark Chocolate Fudge, etc) , I prefer Duncan Hines, but anything similar should be okay.

Chocolate Mousse

  • 1 cup semi sweet chocolate chips
  • 1 cup heavy cream
  • 8oz cream cheese, room temperature
  • 1/4 cup powder sugar
  • 1 teaspoon pure vanilla
  • 1/4 teaspoon salt

The BEST Chocolate Buttercream

  • 1/2 cup chocolate chips
  • 1/2 cup heavy cream , (plus more if needed at the end)
  • 3 sticks (or 1 1/2 cups) unsalted butter , left out at room temperature for 10 minutes
  • 1 pinch salt
  • 1 Tablespoon vanilla
  • 1/2 cup cocoa powder
  • 7-8 cups powdered sugar

Extras

  • 2 cups chocolate shavings, chocolate curls, mini chocolate chips, or chocolate jimmies/sprinkles
  • 1/2 cup cocoa powder on top , (sifted right on the cake)

Instructions
 

Chocolate Cake

  • Preheat the oven to 325 degrees (convection bake) and prep 3 6" pans with a swipe of shortening and dust of flour. Set aside (you will bake the 3 cakes and slice the cake rounds in half to make 6 layers).
  • In a large bowl, hand-whisk together the buttermilk, sour cream, eggs, vanilla, vegetable oil, cocoa, and flour until thoroughly combined. Sift in the cake mix and gently stir it in to combine (don't overmix!).
  • Bake the cake rounds for 25-27 minutes, then remove from the oven to cool on a wire rack in the pan for about 30 seconds. Flip the cake rounds over to finish cooling completely. Wrap up and freeze for a couple hours to overnight. When you're ready to stack your cake, you can keep them three layers, or use a serrated knife to make 6 layers.

Mousse Filling

  • Place your metal mixing bowl and metal whisk attachment into the freezer for 5 minutes until chilled. Attach the bowl and whisk to your stand mixer.
  • Microwave your chocolate in a small glass dish for 30 seconds and stir. Repeat, stir. Repeat one more time if needed, then stir until smooth and silky. Let cool to a little above room temperature.
  • Add in the heavy cream and start the speed on low for about 1 minute. For the next minute or two, slowly increase the speed until you're at full speed and have reached stiff peaks. Add to a separate bowl and set aside (you're going to need your mixing bowl again for the next step).
  • Add the room temperature cream cheese and powdered sugar to the used stand mixer bowl with a paddle attachment and whip up until it's light and fluffy. Add in the vanilla and salt and whip up again.
  • Add in the white chocolate little by little, and make sure it's whipping in smoothly (NOTE: if you notice it's turning into little white bits in the mixture, you need to heat it up just a little bit again before adding it in again). Whip up again until it's all combined.
  • Carefully and gently fold in the whipped cream mixture until a thick and luscious mousse forms. Don't overwork the mousse – let it keep as much air as possible.
    Use immediately or store in the fridge up to a week for best results.

The BEST Chocolate Buttercream

  • In a small microwave-safe bowl, stir together the chocolate chips and heavy cream. Heat for about 30 seconds and stir. Repeat again until the mixture is melted, then stir until there are no lumps. Set aside.
  • In the bowl of a stand mixer, whip up the butter until it's light and fluffy. Add in the salt, vanilla, cocoa, and the room-temperature(ish) chocolate ganache mixture you created.
  • Slowly add in the powdered sugar, then a little more heavy cream if needed. Turn the mixer to high speed and whip up until it's lighter and fluffier in texture and color.

Assembly

  • Place a cardboard cake round on a cake turntable. Spread on a little bit of buttercream in the center of the round and spread it out with an angled icing spatula. Place down the first chilled cake layer in the center. Add on a thin layer of buttercream on top and smooth it out with an angled icing spatula again. Pipe a dam around the outside rim of the cake, then pipe/add in a layer of mousse.
  • Place the next cake layer on top, then repeat with the rest of the layers – making sure to line the layers up evenly. After adding on the top cake layer, crumb coat the cake by spreading the buttercream in a thin layer around the entire cake. Freeze for 2 minutes to set.
  • Using a wooden spoon, hand-beat out any air bubbles in the remaining buttercream. Spread on a final layer of buttercream around the entire cake, using a cake scraper for clean lines and edges. Press on the chocolate curls around the entire cake and sift on a little cocoa powder on top.