Double Chocolate Layer Cake with Milk Chocolate Sour Cream Frosting
 
 
Double the chocolate means double the fun?! That's definitely true where this double chocolate layer cake is involved! Two rich chocolate cake layers are topped with a sweet and slightly tangy milk chocolate sour cream frosting - yum!
Yield: 9-inch layer cake
Ingredients
For the cake
  • 1½ cups cake flour
  • ¼ cup + 1 tbsp unsweetened cocoa powder
  • ¼ cup (70 g) finely chopped bittersweet chocolate
  • 1 cup + 1 tbsp sugar
  • ½ tsp baking powder
  • ½ tsp baking soda
  • ½ tsp kosher salt
  • 1 cup buttermilk
  • 2 tsp vanilla extract
  • 2 large eggs
  • ⅓ cup packed brown sugar
  • 1 cup canola oil
For the frosting
  • 8 oz bittersweet chocolate, chopped
  • 4 oz milk chocolate, chopped
  • 1 cup unsalted butter, softened
  • 1 cup powdered sugar
  • 1 cup sour cream, room temperature
  • 2 tsp vanilla extract
  • ¾ tsp kosher salt
Instructions
For the cake
  1. Heat oven to 350F. Grease a 9-inch cake pan with baking spray, line it with parchment paper and grease the parchment paper. Set aside.
  2. Melt the chocolate, either in a double boiler on the stove or in the microwave. Allow it to cool slightly, about 5 minutes.
  3. Meanwhile, sift together the cake flour and cocoa powder. Whisk in ½ cup of the sugar, the baking powder, the baking soda, and the salt. Set aside.
  4. In a small bowl, combine the buttermilk and vanilla. Set aside.
  5. In the bowl of a stand mixer fitted with the whisk attachment, combine the eggs, brown sugar, and remaining white sugar. Whip in medium-high speed until very pale and tripled in volume, about 5-6 minutes. Scrape down the sides of the bowl.
  6. Reduce the speed to medium and slowly stream in ½ cup of the oil. Add the melted chocolate and mix to combine. Finally, slowly stream in the remaining ½ cup of oil. Scrape down the sides of the bowl.
  7. Turn the mixer to medium-low and then add in the buttermilk-vanilla mixture in a slow stream. Mix until just incorporated, then scrape down the sides of the bowl again. Remove the bowl from the machine.
  8. Add in the dry ingredients in 3 additions, folding it in by hand with a spatula until just combined. Pour the batter into the prepared pan and bake until a toothpick comes out with just a few moist crumbs, about 50-55 minutes, rotating the pan halfway through.
  9. Remove from the oven and allow to cool for 5-10 minutes on a wire rack before turning out the cake onto a 9-inch round cake board. Cool to room temperature before splitting and frosting.
For the frosting
  1. Combine both chocolates in a small bowl and melt either in a double boiler or in the microwave. If microwaving, make sure to stir after each 30 minute increment. Once melted, set aside to cool to room temperature.
  2. Once chocolate is cool, place the butter and powdered sugar in the bowl of a stand mixer fitted with the paddle attachment. Cream together for 5 minutes on medium-high speed until fluffy and pale. Scrape down the bowl, turn the mixer speed to medium-low and add the sour cream. Mix until incorporated then add in the cooled chocolate, vanilla, and salt. Turn the mixer up to medium-high speed and beat for 1 minute.
To assemble
  1. Cut the cake in half, into two layers. Set the top layer aside.
  2. Spread about ¾-1 cup of the frosting on top of the bottom layer to fill the cake, using an offset spatula to spread the filling into an even layer. Place the top layer atop the frosting.
  3. Use the remaining frosting to frost the cake and decorate as desired.
Notes
Recipe from The Dahlia Bakery Cookbook: Sweetness in Seattle
Recipe by Joanne Eats Well With Others at https://joanne-eatswellwithothers.com/2017/09/double-chocolate-layer-cake-with-milk-chocolate-sour-cream-frosting.html