A dark chocolate cake with the star ingredient blackberry. This berry is the key ingredient for the buttercream and homemade filling! Hersheys special dark cocoa powder gives this cake a gentle chocolate note!
The herb flavor of the blackberry pairs perfectly with the dark chocolate cake layers. This cake is not only for chocolate fans but for berry lovers as well!
My buttercream split. - Why?
When too much water is added to the buttercream the fat will separate from the water. To avoid it you try to reduce the water content of any added flavors.
If the buttercream separated you can trouble shoot with adding powdered sugar and butter. Make sure to whip the butter in a separate bowl until white and fluffy before adding it to the rest of the buttercream.
Blackberry Dark Chocolate Cake
Ingredients for 3 8-inch layers
1 3/4 cups (310 g) all-purpose flour
3/4 cup (80 g) cocoa powder
1 1/2 tsp baking powder
1 1/2 tsp baking soda
1 tsp salt
2 cups (400 g) sugar
1/2 cup (120 ml) vegetable oil
2 large eggs
2 tsp vanilla extract
1 cup (240 ml) butter milk
1 cup (240 ml) coffee
For the blackberry buttercream:
6 large egg whites
1 1/2 cups (300 g) sugar
2 cups (450 g) butter, softened
3 tsp vanilla extract
1 1/2 cups blackberries
For the blackberry filling:
1 cup (210 g) fresh blackberries
2 tbsp sugar, optional
2 sheet gelatin or 2 tsp powdered gelatin
For the chocolate ganache:
1/4 cup (120 ml) heavy cream, hot
1/2 cup (85 g) chocolate chips
In a big mixing bowl combine eggs, salt, buttermilk, oil and sugar. Mix with a hand mixer until foamy and lighter in color. Sift in flour, baking powder, baking soda and cocoa powder. Mix on low until almost combined, then add the hot coffee. Mix until smooth.
Divide between three greased and lined 8 inch baking pans. Bake at 350 °F for about 25 minutes. Insert a skewer to test if the cake is baked completely. Let the layers cool on a cooling grid. After 4 minutes take them out of the baking pan and let them cool on a parchment paper on a cooling grid.
To make the filling use a medium sized pot and add the blackberry from the filling and buttercream. I like to puree the berries before with a food processor. Place the pot on a stove top and heat it at medium heat until it comes to a simmer. In the meantime soak gelatin in cold water. If you are using granulated gelatin let it bloom in 2 tbsp water for 5 minutes. After 5 minutes the majority of the liquid should be evaporated. Turn the heat off and let the blackberry filling cool for 3 minutes. Separate 1 cup of the reduced blackberry sauce for the buttercream, then mix in the bloomed gelatin. Mix it with a spatula or hand mixer until smooth. If desired add some sugar or honey. Set aside until needed.
For the Swiss meringue buttercream whisk egg whites and sugar in a fat-free heatproof bowl and place it on a pot with simmering water (bain-marie). Whisk it continually until soft peaks form for about 10 minutes.
Take out the water bath and keep whisking the meringue with a handmixer until stiff peaks form. Mix in the butter in small pieces. Keep mixing it until it comes together in a smooth buttercream. Add the vanilla and 1 cup of reduced blackberry sauce. Mix it until smooth.
To decorate the cake, place the bottom layer on a plate and spread a thin layer of blackberry buttercream on top and smooth it. Pipe a boarder with buttercream. and top it with half of the filling, spread it and cover it with buttercream. Add the second cake layer and repeat the step. Then apply the last layer and cover the cake with blackberry buttercream on the top and its side. Smooth it out and let it cool in the fridge for about 40 minutes or place it in the freezer for about 10 minutes.
When the cake is cooled add the second layer of buttercream and smooth it. Place the cake in the fridge for about 30 minutes to make sure it is very cold before the ganache drip is applied.
Prepare the dark chocolate ganache while the cake is resting in the fridge. Heat heavy cream in a small sauce pan. Cut chocolate into small pieces and add it to a small bowl or measuring cup. When the heavy cream is hot to the touch pour it over the chocolate. Let it sit for 3 minutes, then whisk it until it comes together. It should have a smooth consistency but not be too runny. Let it cool for about 5 minutes before transferring it into a piping bottle. Then decorate the cake with the ganache drip on its sides.
Decorate the cake with fresh fruits and pipe a boarder of buttercream swirls on top of the cake!
I like to change the bowl after the meringue was cooking on the water bath to a cold bowl. That makes mixing the meringue easier as it reaches room temperature faster.
The buttercream can stay at room temperature for about 2 days. Then it should be moved in the fridge. Just whip it up for 10 minutes before using.
To avoid splitting of the buttercream cook the blackberry sauce until thickened. The reduced water content will help to create a smooth and rich blackberry flavored buttercream.