Raspberry-Chocolate Mousse Chocolate Cake

By now I’m sure you all realize that my family loves dark chocolate. Thus, this cake that I made for my birthday was a big hit! Ganache is my favorite way to frost chocolate cakes—you get an intense chocolate kick without the super sweet sugary feel of typical frosting. The raspberry-chocolate mousse in the middle also had a dark chocolate flavor with just a hint of raspberry. The original recipe from King Arthur Flour’s Baking Sheet used a different chocolate cake recipe, but I used their recipe for Favorite Fudge Birthday Cake instead because it is super easy to make and always turns out very moist, fudgy, and delicious.

Favorite Fudge Birthday Cake

2 cups (14 ounces) sugar
2 cups (8 1/2 ounces) King Arthur Unbleached All-Purpose Flour
2 tablespoons (3/8 ounce) Instant ClearJel® or cornstarch
3/4 cup (2 1/4 ounces) Double-Dutch Dark Cocoa or Dutch-process cocoa
2 teaspoons baking powder
2 teaspoons espresso powder
1/2 teaspoon baking soda
1 teaspoon salt
4 large eggs
3/4 cup (5 1/4 ounces) vegetable oil
2 teaspoons vanilla extract
1 1/4 cups (10 ounces) water

Preheat the oven to 350°F. Lightly grease and flour (or grease, then line with parchment, then grease again, or use Baker’s Joy) two 8" x 2" round cake pans. Note: These pans need to be at least 2" tall; if you have non-standard, shorter 8" pans, substitute 9" round pans.

Whisk together the dry ingredients. Add the eggs, oil, and vanilla, beating until smooth. Gradually add the water, beating until smooth. Pour the batter into the prepared pans.

Bake the cakes for 25 to 35 minutes, or until a cake tester inserted into the center comes out clean. Cool the cakes in the pan for 15 minutes, then turn them out of the pans to cool completely on a rack.

Raspberry-Chocolate Mousse

2 cups (16 ounces) heavy cream
½ cup (3 ½ ounces) granulated sugar
1 cup (6 ounces) coarsely chopped unsweetened baking chocolate, melted and cooled (I would recommend using bittersweet instead of unsweetened)
1 pint (8 ½ ounces) fresh red raspberries

Place heavy cream and sugar in a large mixing bowl and whisk on medium-high for 2 minutes until firm peaks form. Add 1 ½ cups of the whipped cream to the cooled, melted chocolate and use a rubber spatula to fold together until thoroughly combined. Add the combined whipped cream and chocolate to the remaining whipped cream and mix on medium-high for 30 seconds. Scrape the sides and bottom of the bowl, add the raspberries, and mix on medium for another 10 seconds. Cover and refrigerate until ready to use.

Chocolate Ganache

12 ounces bittersweet chocolate chips
9 ounces heavy cream

Place chocolate and cream in a medium microwaveable bowl. Microwave on high for about 2 minutes, until chocolate starts to melt, then whisk until smooth. Cool to room temperature. Be patient—this takes a long time to cool. The ganache will be very thin at first, but then will gradually thicken into a spreading consistency. Don’t try to speed up this process by putting the ganache in the fridge—it will set up too firmly and be more like fudge than icing.

Raspberry Sauce

2 cups (10 ounces) frozen whole raspberries (Note: I used a 12 ounce package that I thawed before using.)
2 teaspoons cornstarch (Note: I used 2 teaspoons cornstarch and 2 teaspoons Instant ClearJel)
¼ cup (1 ¾ ounces) granulated sugar (I used 1/3 cup since I increased the amount of berries)

Mix sugar and cornstarch together in a small saucepan. Add thawed raspberries. Cook over medium heat; bring to a boil to thicken. Remove from heat and strain the mixture to remove seeds.

To assemble the cake:

Set aside 1 cup of the mousse for decorating the cake. Trim the tops of the cake layers if necessary to remove any dome. Put one layer, cut-side down, on a serving plate. Line the plate with waxed paper or parchment to keep it clean while you assemble the cake. Fill the cake layers with the remaining mousse. Refrigerate the cake to set the mousse while you make the ganache.

Once the ganache has reached room temperature, pour it over the cake and use an offset spatula to smooth over the top and sides. Refrigerate the cake for 15 or more minutes to set the ganache.

Once the ganache is firm, pipe rosettes of reserved mousse (use a large, open star tip so the raspberry bits won’t clog the tip) around the outer edge of the top of the cake; make sure the edges of the rosettes touch each other. If you have enough mousse left, you can also pipe a border around the lower edge of the cake. Pour the raspberry sauce on the top of the cake, and spread it all the way to the rosettes with a small offset spatula.

Decorate the top of the cake with extra fresh raspberries if desired. Refrigerate the finished cake until ready to serve.