This Chocolate Cake with Chocolate Mousse Filling belongs in a baking contest! It’s a simply amazing moist chocolate cake filled with dark chocolate mousse, and a warm chocolate frosting poured on top!
I probably developed a love for baking before my love for general cooking. As a little girl my idea of fun was inventing cookie recipes. My mom would my sister and me have free reign in the kitchen to experiment with our friends.
The cookies never turned out great but it was such a fun learning experience for us and we just loved creating something out of nothing, even if it didn’t taste great.
That’s what I love about baking. You can create something beautiful and amazing out of the most simple ingredients! This Chocolate Cake with Chocolate Mousse filling is the perfect example of that. An easy homemade chocolate cake recipe, paired with the simplest mousse recipe you will ever find, but put them together and you create a masterpiece! For something similar, check out my Chocolate Cake with Raspberry Filling.
How do you make chocolate mousse?
The ingredients you need to make chocolate mousse are really simple: water, cocoa powder, chocolate chips, whipped cream, and sugar.
Start by mixing the cocoa powder and hot water together until smooth. Melt the chocolate chips in the microwave, or using a double boiler. I use toll house or Ghirardelli brand chocolate chips and follow the instructions on the package for melting them in the microwave.
Add the cocoa powder mixture to the melted chocolate and stir until smooth. Allow to cool to room temperature.
Whip the cream and sugar together in a large mixing bowl until very stiff peaks. Add the cooled melted chocolate and gently fold the mixture together to combine. Refrigerate until ready to use.
This easy chocolate mousse recipe does not use eggs, like some recipes, and will last in the fridge in an airtight container for up to 5 days. Fold it again gently with a spatula before using.
How do you make chocolate mousse cake?
This chocolate mousse cake has three parts: chocolate cake, homemade chocolate mousse, and chocolate frosting. If you don’t want to make the cake from scratch, you could use a box cake mix.
Start by baking the chocolate cake in two 8 or 9 inch round cake pans.
Once the cakes have cooled use a sharp serrated knife to torte them in half, lengthwise, so you have four thin layers of chocolate cake.
Place the first cake layer on your serving tray. Smooth a thin layer of chocolate mousse over it, and top with the next layer of cake. Repeat to assemble a cake with chocolate mousse between each layer.
You can smooth any extra chocolate mousse you have over the outsides of the entire cake to make a”crumb” coat and seal in all of the crumbs.
Refrigerate the cake for at least 30 minutes (or up to 1-2 days, covered) while you make the chocolate frosting.
The warm chocolate frosting, similar to a ganache, is made on the stove and gets poured over the assembled cake. Be sure to allow the frosting to cool for at least 15-20 minutes before pouring over the cake. You want it soft enough to still be “pourable” but you don’t want it to be so warm that it melts the mousse into a puddle.
You can lay pieces of parchment paper around, and gently under the edges, of the cake to catch the frosting as it drips down. I usually just pour the frosting slowly and catch it as it comes down the sides of the cake, smoothing it along the sides of the cake.
This really is the BEST chocolate cake ever. It belongs on a restaurant dessert menu, or in a baking contest, if I do say so myself. It’s a must-try for anyone who loves chocolate!
How to store chocolate cake with chocolate mousse:
This cake is best stored, covered, in the fridge.
The cake rounds can be made in advance and frozen. Once baked, cool them completely and then wrap them in a double layer of plastic wrap. Place them in a freezer ziplock bag and freeze for up to 3 months.
The mousse could also be made up to 5 days in advance, stored in the fridge (although its texture is best the day of).
Consider trying these popular desserts:
- German Chocolate Cake
- Snickerdoodles Bars
- Mississippi Mud Brownies
- Chocolate Mousse Cheesecake
- Mrs. Fields Oatmeal Chocolate Chip Cookies
Chocolate Cake with Chocolate Mousse Filling
- 2 cups granulated sugar
- 1 3/4 cups all-purpose flour
- 3/4 cup unsweetened cocoa powder
- 1 1/2 teaspoons baking powder
- 1 1/2 teaspoons baking soda
- 1 teaspoon salt
- 2 large eggs
- 1 cup milk , or buttermilk
- 1/2 cup oil (vegetable or canola oil)
- 2 teaspoons vanilla extract
- 1 cup boiling water
For the chocolate mousse filling:
- 1/2 cup hot water
- 4 Tablespoons unsweetened cocoa powder
- 1 1/2 cups semi-sweet chocolate chips
- 2 cups heavy whipping cream
- 2 Tablespoons granulated sugar
For the chocolate frosting
- 6 Tablespoons milk
- 3 Tablespoons unsweetened cocoa powder
- 1/2 cup butter (one stick)
- 3 3/4 cups powdered sugar
- Heat oven to 350°F. Grease and flour two 8 or 9 inch round baking pans. (I like to line the bottom of mine with wax or parchment paper).
- Stir together sugar, flour, cocoa powder, baking powder, baking soda and salt in large bowl.
- Add eggs, milk, oil and vanilla; beat on medium speed of mixer 2 minutes.
- Stir in boiling water (the batter will be thin). Pour batter into prepared pans.
- Bake for about 30 to 35 minutes or until a toothpick inserted in the center comes out clean.
- Allow cake to cool in the pan for 5 minutes and then remove to wire cooling racks. Cool completely. (You could freeze the cake rounds at this point, if desired. See note above)
For the chocolate mousse filling:
- Stir the cocoa powder and hot water together. In a double- boiler (or in the microwave) melt the chocolate chips, just until smooth. Add the cocoa mixture to the melted chocolate chips and stir well to combine. Allow to cool to room temperature.
- In a separate large bowl, beat the cream and sugar until very stiff peaks form. Add the chocolate mixture and fold in with a spatula until well combined. Refrigerate until ready to use, up to 5 days.
For the chocolate frosting:
- In a medium saucepan, add milk, cocoa, and butter. Bring to a boil. Remove from heat.
- Add powdered sugar and mix with electric beaters to get rid of any lumps. Allow to cool for 15-20 minutes, stirring occasionally.
- Once cakes have cooled, use a sharp serrated knife to torte each cake (cut each cake evenly in half, horizontally, so that you end up with four, thin, 9'' cake pieces).
- Place your first cake layer on your cake serving plate. Spread a big spoonful of mousse on top of that cake layer. Repeat with the remaining cake layers, adding a layer of mousse filling between each layer of cake.
- Use remaining mousse filling to spread it evenly around the entire outside and top of the cake. Refrigerate for 30 minutes.
- (I usually make the warm chocolate frosting while the cake is in the fridge.)
- Remove cake from fridge and very slowly pour the cooled chocolate frosting over the top. Use a spatula or knife to gently spread the frosting evenly over the outside of the cake as you pour.
- Refrigerate until ready to serve!
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*I first shared this recipe in May 2014. Updated May 2018.