Chocolate Mousse Cake (Cake Mix)

We have a decadent new cake recipe to share with you for easy Chocolate Mousse Cake! This one's for all of the chocolate lovers! Nobody would guess that it all begins with a box of cake mix.

Rich chocolate cake layers are filled with a luscious, simple chocolate mousse filling.

The mousse filling is a "mock mousse" made with instant pudding mix and cream. It is heavenly, and mixes up in minutes.

The Chocolate Mousse Cake is frosted with our go-to chocolate buttercream frosting- it is silky smooth, delicious, and great for piping also!

Why we Love it

There are so many reasons to love this Chocolate Mousse Cake! Here are just a few:

• Super easy chocolate cake and filling yet beautiful & impressive!
• Triple dose of chocolate!
• Ultra moist cake with wonderful chocolate flavor, just as with our Marble Cake Mix Recipe that also calls for sour cream & pudding!
• Perfect birthday cake recipe, holiday cake, or just because!

Ingredients for Chocolate Mousse Cake Layers

Here is a look at some of the star ingredients for our chocolate cake layers.

These add-ins not only enhance the texture and flavor of the chocolate box mix, but also give us enough batter to fill three 8 inch round cake pans.

Tips for Ingredients

Remember to find the full ingredient list and instructions at the bottom of this post!

Instant Chocolate Pudding: This enhances the chocolate flavor of the cake and gives it a softer texture.

Devil's Food Cake Mix: We used Duncan Hines Perfectly Moist for this recipe but you can substitute with whatever your preferred cake recipe is.

Sour Cream: We often use sour cream in our doctored cake mix recipes (like WASC Cake for instance.) It adds richness to the cake and also gives the cake a nice texture. We use "full fat" sour cream.

How to Make Chocolate Mousse Cake

You can find the full, printable Chocolate Mousse Cake recipe at the bottom of this post. Here is a quick look at our steps!

• Preheat the oven to 325 degrees F. Grease and Flour three 8 inch round pans. As an optional step, we also like to line the bottom of our pans with parchment paper.
• In the bowl of your mixer, add the chocolate cake mix, all purpose flour, sugar, and chocolate pudding mix. Whisk to blend.

• Add the remaining ingredients to the bowl (sour cream, vegetable oil, water, eggs, and vanilla extract). Mix on low speed with an electric mixer (using a paddle attachment if using a stand mixer) for about 30 seconds.
• Scrape down the sides and bottom of the bowl as needed and mix on medium speed for two minutes. The batter should look well blended.

• Divide the chocolate cake batter between the three prepared 8 inch round cake pans.

• Bake at 325℉ for approximately 20-25 minutes or until the layers spring back when lightly touched, or a toothpick can be inserted and removed with just a few moist crumbs attached.

• Allow the baked chocolate cake layers to cool in their pans on a wire rack for 10 minutes before turning out. Make sure that they are completely cool before frosting!

Easy Chocolate Mousse Filling

We have been using this easy chocolate mousse filling as well as other flavor variations for years! It is a simple combination of heavy cream and instant chocolate pudding mix.

The result is a light and luscious, thick filling with a mousse-like consistency. You can see delicious variations of this filling using different flavors of pudding in our Mocha Cake, Pineapple Cake, Banana Pudding Cake, and Orange Dreamsicle Cake just to name a few! We also use it as a quick vanilla filling in our easy Boston Cream Pie!

Chocolate Frosting

For the frosting, we used our classic chocolate buttercream. This is our go-to for chocolate cakes. It is a simple combination of softened butter, confectioners sugar, unsweetened cocoa powder, a splash of milk and a pinch of salt.

Assembling the Chocolate Mousse Cake

Before assembling the cake, make sure that your cake layers are room temperature (or chilled).

Place the first cake layer on your cake base or pedestal. Then spread with chocolate mousse filling.

*If you added a bit more cream and your mousse is on the softer side, it is a good idea to first pipe a buttercream dam around the top edge of the cake layer (about ¼-1/2 inch from the edge) before filling with mousse.

However, if your mousse filling seems fairly thick, a dam isn't necessary to keep the filling contained.

You can see in the photo below that I piped a dam out of habit, but it wasn't really necessary for this filling ;0)

Top with the second chocolate cake layer are repeat. Top with the third cake layer and fill in any remaining gaps between the layers with buttercream.

Next, I frosted the top and sides of the cake with a thin layer of buttercream. This is the crumb coat.

At this point, it is best to chill the cake to firm everything up before the final layer of chocolate buttercream. Chill for 15 minutes in the freezer or longer in the refrigerator to firm up the frosting.

Decorating the Cake

I applied the second layer of chocolate buttercream to the chilled cake and then used my spatula to add additional texture.

Next, I piped a top buttercream border of stars and rosettes using a 1M piping tip. (You can check out our video tutorial on Star Tip Piping basics for more instruction!)

Recipe FAQs

More Chocolate Cakes

We have so many more chocolate cakes to share with you! Some of our favorites are our German Chocolate Cake, Black Forest Cake, Oreo Ice Cream Cake, and Almond Joy Cake.

Thanks so much for stopping by today! We hope that you enjoy this easy Chocolate Mousse Cake! It would make a perfect birthday cake recipe for chocolate lovers, and is certain to make any occasion feel more special.

Make sure to check out our full collection of Cake Recipes, including our favorite cake recipes from scratch as well as our favorite cake mix recipes!

Chocolate Mousse Cake

BY Melissa and Bebe

This easy Chocolate Mousse Cake is so moist, decadent, and impressive! Nobody would ever guess how simple the cake and mousse filling are to make!

Prep Time: 30 minutes mins

Cook Time: 25 minutes mins

Course: Dessert

Servings: 15

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Ingredients

• ▢ 1 15.25 oz Box Devils Food Cake Mix (We used Duncan Hines Devils Food Cake- Perfectly Moist
• ▢ ½ cup (60g) All Purpose Flour
• ▢ ½ cup (100g) sugar
• ▢ 1 3.9 oz small box Chocolate Instant Pudding Mix. (We use Jello Brand-Do not make pudding, just add the dry powder.)
• ▢ 1 cup (227g) Sour Cream
• ▢ ½ cup (108g) Vegetable Oil (we use canola)
• ▢ 1 ¼ cup (302g) water
• ▢ 3 large eggs room temperature
• ▢ 2 ½ teaspoons (10g) vanilla extract

For the Easy Chocolate Mousse Filling

• ▢ 1 small box instant chocolate pudding 3.9 oz- We recommend sifting the Pudding Mix (to prevent graininess)
• ▢ 2 cups heavy cream or whipping cream

For the Chocolate Buttercream

• ▢ 3 sticks (339g total) Unsalted Butter, softened (Do not soften in the microwave. You can slice butter into small slices and lay flat on wax paper to speed up softening.)
• ▢ 7 cups powdered sugar adjust slightly up or down to your liking
• ▢ 1 cup (82g) unsweetened cocoa
• ▢ ¾ cup (180g) milk plus additional as needed for desired consistency (add in very small increments)
• ▢ 2 teaspoons (12g) vanilla extract
• ▢ 1 teaspoon (6g) salt

Instructions

Instructions

• Preheat the oven to 325 degrees F. Grease and Flour three 8 inch round pans. As an optional step, we also like to line the bottom of our pans with parchment paper.
• In the bowl of your mixer, add the chocolate cake mix, all purpose flour, sugar, and chocolate pudding mix. Whisk to blend.
• Add the remaining ingredients to the bowl (sour cream, vegetable oil, water, eggs, and vanilla). Mix on low speed for about 30 seconds.
• Scrape down the sides and bottom of the bowl as needed and mix on medium speed for two minutes. The batter should look well blended.
• Bake at 325℉ for approximately 20-25 minutes or until the layers spring back when lightly touched, or a toothpick can be inserted and removed with just a few moist crumbs attached. Baking times may vary depending on your oven and the type of pans used. Dark pans may bake slightly more quickly.
• Allow the baked cake layers to cool in their pans on a wire rack for 10 minutes before turning out. Make sure that they are completely cool before frosting!

Chocolate Mousse Filling

• Combine the sifted chocolate pudding mix and heavy cream in a mixing bowl. I prefer to mix with a hand held mixer, but a whisk is fine too. If using a mixer, start on low speed until well combined.
• Then, switch to high speed and whip the pudding until thick and fluffy. If mousse is too thick, add more heavy cream bit by bit until you reach a nice, easily spreadable consistency.
• If mixing by hand, simply whisk rapidly for a couple of minutes or until mixture is nice and thick (but still very easily spreadable). Refrigerate until ready to use.

Chocolate Buttercream

• Add butter and mix on low to medium speed until smooth. Add vanilla and blend into the butter. Add powdered sugar, salt, and sifted cocoa powder.
• Add most of the milk. Begin mixing at low speed so you won't have a cloud of powdered sugar in your kitchen.
• Continue to mix adding remaining milk as needed. It may take 5 to 6 minutes to reach the smoothness and consistency you like. It will take longer if using a hand mixer. As you mix the frosting will become very smooth. You can add additional milk (1 Tablespoon at a time) if the frosting is too thick or additional powdered sugar if too soft.

Assembling and Decorating the Cake

• Place the first chocolate cake layer on the cake base or pedestal. Spread with chocolate mousse filling. Our filling was still fairly thick-- if you added more cream to create a softer consistency of mousse, it is a good idea to pipe a dam of buttercream around the edge of the cake layer about ¼-1/2 inch from the edge, using a piping bag with the tip snipped away. Then, spread the mousse onto the cake within the dam.
• Top with the second cake layer and repeat. Top with the third cake layer and fill in any remaining gaps between the cake layers with chocolate buttercream.
• Crumb coat the top and sides of the cake with a thin layer of buttercream. At this point, we like to chill the cake in the freezer for 15 minutes or in the refrigerator for longer, to firm everything up. Then, add the final layer of buttercream and decorate to your liking.
• We added texture with a small offset spatula, and then piped a top border of rosettes and starts using a 1M piping tip.

Notes

This cake should be refrigerated because of the cream filling. It is best to use an airtight container or cake dome.

However, for best flavor and texture, it is best to remove the cake from the refrigerator a couple of hours before serving.

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