Chocolate Brownie Mousse Cake


Heavy clouds float high above me. They push and prod at the sky, hiding the sun from reaching me miles below them. Cold blasts of wind shake trees bare and scare away the green. Winter brings with it the dull, drab days the beg to be wrapped in handed-down quilts, fluffy sweaters and scarfs of all colors. It also brings with it holidays, get togethers, special meals and birthdays.


This weekend was my mother’s birthday. I baked this for her. We may not get snowy days here in Texas but that doesn’t stop us from having snow-dusted cakes.


Like most of my recipes, this one has quite a few parts – we’ll call it a special occasion recipe. That being said, it is well worth it. The dense brownie-like chocolate cake with the light and fluffy chocolate mousse play so well together. The sweet, chocolate icing brings it all together! If you’re a chocolate lover, then you need to make this cake. Not to mention, the diamond and triangle pattern formed will impress your family and friends. And they don’t need to know how easy it is to do.



Chocolate Brownie Mousse Cake
Recipe by:
  • 2 layers Chocolate Brownie Cake (recipe below)
  • 1 pound
  • Chocolate Mousse (recipe below)
  • 1 pound Milk Chocolate Buttercream Frosting (recipe below)
  • Powdered sugar, for dusting
  1. Bake the cake and prepare the mousse and buttercream and set aside. Store the mousse in the refrigerator.
  2. Remove the cake layers from the pans. Place them on 6 inch cake rounds.
  3. Using a sharp pointed serrated knife, cut a cone out of the center of both cake layers so that you have a cone-shapped recess in each cake layer.
  4. Be sure to leave enough cake around the sides and at the bottom otherwise it may not be able to stand. Also make sure the cones are the same sizes so when assembled a clean diamond mousse filling will form.
  5. Fill each recess with the mousse. Use an icing spatula to make the mousse level with the top of the cake.
  6. Place the mousse-filled layers in the fridge and let chill until firm, about 1 hour.
  7. Remove the layers from the fridge. Carefully invert one layer onto the other, making sure the edges of the cake, and the mousse line up. Remove the cake round from the top of the cake.
  8. Ice the cake with the prepared buttercream frosting.
  9. Tip: Completely the top of the cake first, then the sides by placing extra icing on the top and moving it down over the sides of the cake.
  10. Dust the top of the cake with powdered sugar for a snow-dusted effect.



Diamond-filled cakes: While this wont work with all fillings and cakes, it works well with fillings like mousse that, when refrigerated, become firm and able to support the weight of the cake on top. Below is a diagram on how to achieve the affect.



Chocolate Brownie Cake: The very high moisture and fat content in this recipe makes a very dense, brownie-like cake. It is normal if the center collapses or does not rise fully.

Chocolate Brownie Mousse Cake
Recipe by:
  • 6 ounces all-purpose flour
  • 12 ounces sugar
  • 2 ounces unsweetened cocoa powder
  • 1 teaspoon baking soda
  • 1 teaspoon baking powder
  • ¾ teaspoon salt
  • ½ cup buttermilk
  • ½ cup sour cream
  • 3 ounces unsalted butter, melted
  • 1 teaspoon vanilla
  • ¾ cup hot coffee
  1. Preheat the oven to 350°F. Butter and flour both cake pans. Set aside.
  2. Mix the dry ingredients (flour, sugar, cocoa powder, baking soda, baking powder and salt) together. Set aside.
  3. Mix the buttermilk, sour cream and melted unsalted butter together.
  4. Pour the buttermilk mixture into the dry ingredients. Mix until a thick batter forms.
  5. While mixing, add the coffee and vanilla. Mix until the mixture is homogeneous.
  6. Pour the batter evenly into the prepared cake pans.
  7. Bake the cakes in a preheated oven for 35 to 40 minutes or until a toothpick inserted into the center comes out clean.
  8. Let cool before handling.

Chocolate Mousse: Chocolate mousse is fairly easy to make. This recipe, adapted from Bo Friberg, uses boiled honey to cook the eggs and create structure in the mousse. Anytime you melt chocolate, you want to make sure to do it over barely simmering water in a bain marie or a large glass bowl placed over a pot. Take care not to heat the chocolate too much.


Chocolate Mousse
Recipe by:
  • 1 cup heavy cream
  • 2 egg yolks
  • 1½ ounces honey
  • 4 ounces dark chocolate, chopped
  • 2 ounces milk chocolate, chopped
  • ½ teaspoon vanilla
  1. Whip the heavy cream to soft peaks. Set aside in the fridge.
  2. Heat the honey just to the boiling point.
  3. In the meantime whip the egg yolks until they are thick and reach the ribbon stage.
  4. While whisking, pour the honey into the egg yolks. Continue to whip the mixture until it is cool and thick.
  5. In a bain-marie or a bowl placed over barely simmering water, melt the chocolate.
  6. Pour the chocolate into the egg mixture and mix until completely mixed. Add the vanilla and stir in.
  7. Fold the chocolate mixture into the whipped cream until completely mixed together. Take care not to overmix or deflate the mousse during this step.



Milk Chocolate Frosting: Making chocolate buttercream is almost as easy as making buttercream. There is just one extra step of melting chocolate and adding that into the buttercream.  Anytime you melt chocolate, you want to make sure to do it over barely simmering water in a bain marie or a large glass bowl placed over a pot. Take care not to heat the chocolate too much.

Milk Chocolate Buttercream
Recipe by:
  • 8 ounces unsalted butter, at room temperature
  • 3½ cups powdered sugar
  • ½ teaspoon vanilla
  • 6 ounces milk chocolate, chopped
  1. Melt the chocolate over a bain-marie. Set aside to cool slightly.
  2. Beat the butter, sugar and vanilla togther until a thick frosting forms.
  3. Pour in the chocolate and mix until the frosting comes together and is evenly mixed.

AUTHOR - Russell van Kraayenburg

Food nerd. Cookbook author. Founder of Chasing Delicious. Pastry cook at Fluff Bake Bar. Lover of hot dogs.



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