Ingredients:

  • 2 cups (250g) all-purpose flour, spooned and leveled (plus more for dusting pans)
  • ¾ cup (75g) unsweetened cocoa powder
  • 1 ½ teaspoons baking powder
  • 1 ½ teaspoons baking soda
  • ¾ teaspoon salt
  • 1 cup (240ml) buttermilk, room temperature
  • ½ cup (120ml) vegetable oil
  • 2 large eggs, room temperature
  • 1 ½ cups (300g) granulated sugar
  • 2 teaspoons vanilla extract
  • 1 cup (240ml) boiling water
  • 4 cups (480g) fresh blackberries, divided
  • ½ cup (100g) granulated sugar
  • 2 tablespoons water
  • 1 tablespoon lemon juice
  • 1 cup (2 sticks/226g) unsalted butter, softened
  • 3 cups (360g) powdered sugar, sifted
  • ¾ cup (70g) unsweetened cocoa powder
  • ½ teaspoon salt
  • 6-8 tablespoons (90-120ml) heavy cream
  • 1 teaspoon vanilla extract

Instructions:

  1. Preheat oven to 350°F (175°C). Grease and flour two 8-inch round cake pans, then line the bottoms with parchment paper rounds.
  2. Whisk together flour, cocoa powder, baking powder, baking soda, and salt in a large bowl.
  3. In a separate bowl, whisk together buttermilk, oil, eggs, sugar, and vanilla.
  4. Gradually add the wet ingredients to the dry ingredients, mixing until just combined.
  5. Carefully pour in the boiling water and mix until batter is smooth and thin.
  6. Divide the batter evenly between the prepared pans and bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean.
  7. Let the cakes cool in the pans for 10 minutes, then invert onto a wire rack to cool completely.
  8. Combine 3 cups of blackberries, sugar, water, and lemon juice in a saucepan. Simmer over medium heat, stirring occasionally, until the berries break down and the mixture thickens (about 10-15 minutes).
  9. Remove from heat and stir in the remaining 1 cup of fresh blackberries. Let cool completely.
  10. Beat the softened butter with a mixer until light and fluffy.
  11. Gradually add the powdered sugar, cocoa powder, and salt, beating on low speed until combined.
  12. Gradually add the heavy cream and vanilla extract, beating until light and fluffy.
  13. Place one cake layer on a serving plate. Spread a layer of blackberry compote on top.
  14. Frost the top of the blackberry compote with the buttercream, place the second cake layer on top, and frost the entire cake with the remaining buttercream.
  15. Garnish with fresh blackberries and chocolate shavings, if desired.
  16. Chill the cake for at least 30 minutes to allow the frosting to set.