Ingredients:

  • 1 ¾ cups (210 g) All-Purpose Flour
  • 2 cups (400 g) Granulated Sugar
  • ¾ cup (75 g) Dutch-processed Unsweetened Cocoa Powder
  • 1 ½ tsp Baking Soda
  • ¾ tsp Baking Powder
  • 1 tsp Fine sea salt
  • 2 Large Eggs (room temperature)
  • 1 cup (240 ml) Buttermilk (room temperature)
  • ½ cup (120 ml) Vegetable Oil
  • 2 tsp Vanilla Extract
  • 1 cup (240 ml) Hot Brewed Coffee
  • 2 cups (300 g) Fresh or Frozen Blackberries
  • ¼ cup (50 g) Granulated Sugar (for filling)
  • 1 Tbsp Freshly squeezed Lemon Juice
  • 1 Tbsp Cornstarch
  • 2 Tbsp Cold Water (for slurry)
  • 10 oz (285 g) Good Quality Dark Chocolate (60-70%), finely chopped
  • 1 cup (240 ml) Heavy Cream (35% fat)
  • 2 Tbsp Cold Unsalted Butter (cubed)
  • 1 cup (120 g) Powdered Sugar (Optional, for stiffer frosting)

Instructions:

  1. Phase 1: The Blackberry Compote. Combine blackberries, sugar, and lemon juice in a saucepan. Bring to a simmer over medium heat, stirring occasionally. Whisk cornstarch and cold water to form a slurry, then pour into the simmering berries, whisking constantly until thickened (about 1 minute). Remove from heat, cover the surface with plastic wrap, and chill completely.
  2. Preheat oven to 350°F (175°C). Grease and line two 8-inch cake pans with parchment paper.
  3. Whisk together all dry ingredients (flour, sugar, cocoa, baking soda, baking powder, salt) in a large bowl.
  4. In a separate bowl, whisk together eggs, buttermilk, oil, and vanilla. Pour the wet mixture into the dry mixture and mix on low speed until just combined. Carefully pour the hot coffee into the batter while mixing slowly until smooth; the batter will be very thin.
  5. Divide batter evenly between prepared pans. Bake for 30–35 minutes, or until a skewer comes out clean. Cool in pans for 15 minutes before inverting onto wire racks to cool completely.
  6. Phase 3: The Ganache Frosting. Place chopped dark chocolate in a heatproof bowl. Heat heavy cream just until it begins to simmer around the edges, then pour it over the chocolate. Let stand undisturbed for 5 minutes.
  7. Stir slowly from the center outwards until the mixture is entirely smooth and glossy. Whisk in the cold butter cubes until fully incorporated. If using powdered sugar, allow the ganache to cool slightly, then beat in the sugar until light and fluffy.
  8. Phase 4: Assembly. Ensure cake layers are completely cool. Place the first layer on a serving plate and create a dam border using about 1/4 of the cooled ganache. Spoon the chilled blackberry compote inside the dam.
  9. Top with the second cake layer. Frost the entire cake—top and sides—with the remaining ganache. Chill for 30 minutes before slicing.