Ingredients:

  • 2 cups (240 g) All-purpose Flour, sifted
  • ¾ cup (75 g) Unsweetened Cocoa Powder, high-quality, Dutch-processed
  • 1 ½ tsp (7.5 ml) Baking Soda
  • 1 tsp (5 ml) Salt
  • 1 ¾ cups (350 g) Granulated Sugar
  • ½ cup (113 g) Unsalted Butter, softened
  • 2 large Eggs
  • 1 cup (240 ml) Buttermilk
  • 2 tsp (10 ml) Vanilla Extract
  • ½ cup (120 ml) Hot Coffee, freshly brewed
  • 12 oz (340 g) White Chocolate, finely chopped
  • ½ cup (120 ml) Heavy Cream (for melting)
  • 1 tsp (5 g) Powdered Gelatin
  • 2 Tbsp (30 ml) Cold Water (for blooming gelatin)
  • 2 cups (480 ml) Heavy Cream (for whipping), very cold
  • ¼ cup (30 g) Powdered Sugar
  • 8 oz (225 g) Dark Chocolate (60-70% cacao), finely chopped
  • 1 cup (240 ml) Heavy Cream (for ganache)
  • 1 Tbsp (15 g) Unsalted Butter, softened (optional for shine)

Instructions:

  1. Prepare Pans: Preheat oven to 350°F (175°C). Grease and flour two 9-inch cake pans, lining the bottoms with parchment paper circles.
  2. Combine Dry Ingredients: In a large bowl, whisk together the flour, cocoa powder, baking soda, and salt. Set aside.
  3. Cream Butter and Sugar: In the stand mixer bowl, cream the softened butter and granulated sugar until light and fluffy (about 3 minutes).
  4. Add Wet Ingredients: Beat in the eggs one at a time, followed by the vanilla. Slowly incorporate the buttermilk.
  5. Mix Batter: Add the dry ingredients gradually to the wet mixture, mixing on low speed until just combined. Do not overmix!
  6. Activate Cocoa: Carefully pour the hot coffee into the batter and mix until smooth. The batter will be thin—this is correct.
  7. Bake: Divide batter evenly between the two prepared pans. Bake for 30–35 minutes, or until a wooden skewer inserted into the centre comes out with moist crumbs attached.
  8. Cool: Cool the cakes in pans for 10 minutes, then invert onto a wire rack to cool completely.
  9. Bloom Gelatin: Sprinkle the gelatin powder over the cold water in a small bowl. Let stand for 5 minutes.
  10. Melt White Chocolate: Combine the white chocolate and ½ cup heavy cream in a double boiler. Stir until completely smooth. Stir the bloomed gelatin into the warm chocolate mixture until fully dissolved. Set aside to cool to just above room temperature.
  11. Whip Cream: Using a clean bowl, whip the remaining 2 cups of very cold heavy cream and powdered sugar until firm, stiff peaks form.
  12. Fold: Gently fold about a third of the whipped cream into the cooled white chocolate mixture to lighten it. Then, fold the lightened mixture back into the remaining whipped cream until homogenous (no streaks).
  13. Chill Mousse: Immediately refrigerate the mousse for 30–45 minutes until it is just firm enough to spread.
  14. Slice Cakes: Level the cooled cake layers if needed. Slice each layer horizontally once to create four thin layers.
  15. Stack: Place the first cake layer on your serving plate. Spread one-third of the white chocolate mousse evenly over the layer. Repeat this process with the next two layers of cake and mousse. Top with the final cake layer.
  16. Set Cake: Chill the assembled cake in the refrigerator for at least 2 hours to allow the mousse to firm up completely.
  17. Heat Cream: In a small saucepan, bring 1 cup of heavy cream just to a simmer.
  18. Mix Ganache: Place the chopped dark chocolate in a heatproof bowl. Pour the hot cream over the chocolate. Let stand undisturbed for 5 minutes, then stir gently until completely smooth and glossy. Stir in the optional softened butter.
  19. Cool Ganache: Let the ganache cool at room temperature until it reaches the consistency of thick, pourable syrup (about 85–90°F or 30°C).
  20. Glaze: Place the chilled cake on a wire rack over a baking sheet. Pour the ganache over the top centre of the cake, allowing it to naturally drip down the sides.
  21. Final Chill: Refrigerate the finished cake for another 1–2 hours to allow the glaze to set firmly before slicing and serving.