Ingredients:

  • 375g cake flour, sifted
  • 400g granulated sugar
  • 1.5 tsp baking powder
  • 0.5 tsp baking soda
  • 1 tsp fine sea salt
  • 225g unsalted butter, softened to 65°F
  • 60ml neutral vegetable oil
  • 4 large eggs, room temperature
  • 2 large egg yolks, room temperature
  • 1 tbsp pure vanilla extract
  • 240ml full-fat buttermilk, room temperature
  • 450g unsalted butter, softened (for frosting)
  • 120g Dutch-process cocoa powder (for frosting)
  • 600g confectioners' sugar, sifted (for frosting)
  • 60ml heavy cream (for frosting)

Instructions:

  1. Preheat oven to 350°F (175°C). Grease and line two 8-inch round cake pans with parchment paper.
  2. In a medium bowl, whisk together the sifted cake flour, baking powder, baking soda, and sea salt.
  3. Using a stand mixer with a paddle attachment, cream 225g butter and granulated sugar on medium-high speed for 5 minutes until pale and fluffy.
  4. Slowly stream in the vegetable oil while the mixer is running. Add the eggs and extra yolks one at a time, followed by the vanilla extract, ensuring each is fully emulsified.
  5. Reduce mixer speed to low. Alternately add the dry flour mixture and the buttermilk in three batches, beginning and ending with the dry ingredients. Mix just until combined.
  6. Divide batter evenly between the prepared pans. Bake for 28-32 minutes or until a toothpick inserted into the center comes out clean.
  7. Cool cakes in pans for 10 minutes before transferring to a wire rack to cool completely.
  8. For the frosting: Beat 450g butter until smooth. Sift in cocoa powder and powdered sugar. Add heavy cream and beat on high until light and silky. Frost the cooled cake layers.