White Chocolate Mousse Cake

By
Linda Larsen
Linda Larsen
Linda Larsen is a journalist, quick-cooking and slow-cooking expert, and accomplished cookbook author with over 30 years of experience in testing and developing recipes.
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Updated on 12/27/22
White chocolate mousse cake

Sot / Getty Images

Prep: 45 mins
Cook: 25 mins
Total: 70 mins
Servings: 16 servings

This white chocolate mousse cake is a birthday party showstopper. The combination of white cake, white chocolate cream filling, and white frosting not only makes for a beautiful presentation but also a delicious combination of flavors. 

This gorgeous cake takes some time to prepare, but it is very easy, particularly since it begins with a cake mix. You can also make the cake in steps over a few days. Bake the cake one day and reserve it, or freeze it for up to three months. Then make the mousse and frosting another day, and assemble it the same day or the day after. It is perfect for any celebration and is especially appropriate for birthdays. Anyone who loves white cake will think this is the perfect dessert. 

Ingredients

For the Cake:

  • Baking spray

  • 1 (18-ounce) box white cake mix

  • 1 1/4 cups water

  • 1/3 cup oil

  • 3 large egg whites

For the Filling:

For the Frosting:

  • 4 ounces (1/2 cup) unsalted butter, at room temperature

  • 2 cups confectioners' sugar

  • 1 teaspoon pure vanilla extract

  • 2 to 3 tablespoons milk

Steps to Make It

Make the Cake

  1. Gather the ingredients.

  2. Heat the oven to 350 F. Spray 2 (9-inch) round cake pans with a nonstick baking spray that contains flour and set aside.

  3. In a large bowl, combine the cake mix, water, oil, and egg whites. Beat 2 minutes at high speed.

  4. Pour the batter into the prepared pans and bake for 25 to 35 minutes or until a toothpick inserted in the cake comes out clean.

  5. Cool on a wire rack for 15 minutes, then remove the cakes from the pans and cool completely on a wire rack.

Make the Filling

  1. Gather the ingredients.

  2. In a small heatproof bowl, combine the whipping cream with the white chocolate chips. Microwave on 50 percent power, stirring occasionally, for 2 to 4 minutes or until the chips are melted and the mixture is smooth. Set aside.

  3. In another small bowl, beat the mascarpone cheese and vanilla until smooth. Beat in the reserved melted white chocolate chip mixture.

  4. In another separate small bowl, beat the heavy cream with the confectioners' sugar until thick. Fold into the mascarpone mixture and refrigerate for at least 2 hours, or until you're ready to assemble the cake.

Make the Frosting and Assemble

  1. Gather the ingredients.

  2. In a bowl, beat together the butter, confectioners' sugar, vanilla, and enough milk for a smooth spread consistency. Set aside.

  3. To assemble the cake, place 1 cake layer upside down on a serving plate. Top with all of the white chocolate filling.

  4. Place the remaining cake layer, right-side up, on top of the filling. Frost the top and sides of the cake with the frosting. Decorate the top with dollops of frosting, if desired.

  5. Slice and enjoy.

How to Store

Store the cake, covered, in the refrigerator. Bring it out of the fridge 20 minutes before serving.

Recipe Variation

Although it will no longer be a white chocolate-filled cake, you can eliminate the white chocolate in the filling—along with the 2 tablespoons of whipping cream—if you prefer. Simply mix the remaining filling ingredients, adding an extra tablespoon or two of confectioners' sugar to make up for the sweetness of the white chocolate.

Nutrition Facts (per serving)
390 Calories
26g Fat
37g Carbs
4g Protein
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Nutrition Facts
Servings: 16
Amount per serving
Calories 390
% Daily Value*
Total Fat 26g 33%
Saturated Fat 12g 60%
Cholesterol 47mg 16%
Sodium 186mg 8%
Total Carbohydrate 37g 13%
Dietary Fiber 0g 1%
Total Sugars 30g
Protein 4g
Vitamin C 0mg 1%
Calcium 76mg 6%
Iron 1mg 3%
Potassium 86mg 2%
*The % Daily Value (DV) tells you how much a nutrient in a food serving contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.
(Nutrition information is calculated using an ingredient database and should be considered an estimate.)