01 -
Preheat oven to 350°F and grease and flour an 8-inch round cake pan.
02 -
In a bowl, whisk together all-purpose flour, unsweetened cocoa powder, baking powder, baking soda, and salt.
03 -
In a large mixing bowl, beat the softened butter and granulated sugar until light and fluffy, about 3 to 5 minutes.
04 -
Add eggs one at a time, mixing well after each addition, then stir in vanilla extract.
05 -
Gradually add the dry ingredients to the butter mixture, alternating with buttermilk, and mix until just combined.
06 -
Pour the batter into the prepared pan, smooth the top, and bake for 25 to 30 minutes, or until a toothpick inserted in the center comes out clean.
07 -
Allow the cake to cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.
08 -
Puree raspberries and 1/4 cup granulated sugar in a blender. Strain through a fine mesh sieve to remove seeds.
09 -
Whip the heavy cream and vanilla extract until soft peaks form, then gently fold in the melted dark chocolate and raspberry puree until combined.
10 -
Refrigerate raspberry mousse for about 30 minutes to allow it to set.
11 -
Once the cake is completely cool, slice horizontally to create two layers.
12 -
Place the bottom cake layer on a serving plate. Spread half the raspberry mousse over the layer, top with the second cake layer, then spread the remaining mousse on top.
13 -
Chill the assembled cake in the refrigerator for at least 1 hour.
14 -
Heat 1/2 cup heavy cream until just boiling. Remove from heat and pour over chopped dark chocolate. Let stand for several minutes, then stir until smooth.
15 -
Drizzle chocolate ganache over the chilled cake and garnish with fresh raspberries before serving.