Ingredients:

  • 2 cups (250g) All-purpose flour
  • 2 cups (400g) Granulated sugar
  • 0.75 cup (75g) Dutch-processed cocoa powder
  • 2 tsp Baking soda
  • 1 tsp Baking powder
  • 1 tsp Salt
  • 1 cup (240ml) Buttermilk, room temperature
  • 0.5 cup (120ml) Vegetable oil
  • 2 Large eggs, room temperature
  • 2 tsp Pure vanilla extract
  • 1 cup (240ml) Boiling water
  • 5 tbsp (40g) All-purpose flour (for filling)
  • 1 cup (200g) Granulated sugar (for filling)
  • 1 cup (240ml) Whole milk
  • 1 cup (225g) Unsalted butter, softened
  • 1 tsp Vanilla extract (for filling)
  • 1 pinch fine salt
  • 8 oz (225g) Semi-sweet chocolate, finely chopped
  • 1 cup (240ml) Heavy whipping cream
  • 1 tbsp Light corn syrup

Instructions:

  1. Preheat oven to 350°F (175°C). Grease and flour two 9-inch round cake pans and line the bottoms with parchment paper.
  2. Sift 250g flour, 400g sugar, 75g cocoa, baking soda, baking powder, and salt into a large bowl. Whisk to combine.
  3. Add buttermilk, vegetable oil, eggs, and 2 tsp vanilla. Whisk until smooth. Slowly stream in the boiling water while whisking constantly to bloom the cocoa.
  4. Divide batter evenly between pans. Bake for 30–35 minutes or until a toothpick comes out clean. Cool in pans for 10 minutes, then transfer to wire racks to cool completely.
  5. Prepare Ermine filling: Whisk 40g flour and 240ml milk in a medium saucepan over medium heat. Cook, stirring constantly, until it thickens into a heavy paste (roux). Remove from heat and cool completely to room temperature.
  6. Cream 225g butter and 200g sugar for 5 minutes until pale and fluffy. Add the cooled flour paste one tablespoon at a time, beating well after each addition until the filling resembles whipped cream. Stir in vanilla and salt.
  7. Prepare Ganache: Place chopped chocolate in a bowl. Heat heavy cream and corn syrup until simmering; pour over chocolate. Let stand for 5 minutes, then whisk until a glossy emulsion forms.
  8. Assemble: Place one cake layer on a plate. Spread the Ermine filling evenly to the edges. Top with the second cake layer. Pour the warm ganache over the top, allowing it to drip down the sides.