Ingredients:

  • 2 ½ cups (300g) All-Purpose Flour, plus extra for dusting the pan
  • 1 ½ cups (300g) Granulated Sugar
  • 1 tsp Baking Powder
  • ½ tsp Baking Soda
  • ½ tsp Salt
  • 1 cup (240ml) Buttermilk, room temperature
  • ½ cup (120ml) Vegetable Oil (like canola or sunflower)
  • 2 Large Eggs, room temperature
  • 2 tsp Vanilla Extract
  • ½ cup (50g) Unsweetened Cocoa Powder
  • ¼ cup (60ml) Hot Water

Instructions:

  1. Preheat oven to 350°F (175°C). Grease and flour a 9x13 inch baking pan.
  2. In a large mixing bowl, whisk together the flour, sugar, baking powder, baking soda, and salt.
  3. Add the buttermilk, oil, eggs, and vanilla extract to the dry ingredients. Beat until just combined – don't overmix!
  4. Divide the batter evenly into two smaller bowls.
  5. In one bowl, whisk together the cocoa powder and hot water until smooth. Add this mixture to one half of the batter and mix until well combined.
  6. Drop spoonfuls of the vanilla and chocolate batters alternately into the prepared baking pan.
  7. Use a toothpick or skewer to gently swirl the batters together, creating a marbled effect. Be careful not to over-swirl, or you'll lose the distinct patterns.
  8. Bake for 40-45 minutes, or until a toothpick inserted into the center comes out clean.
  9. Let the cake cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.