Ingredients:

  • 2 cups (250g) all-purpose flour
  • 2 cups (400g) granulated sugar
  • 3/4 cup (75g) unsweetened cocoa powder
  • 2 tsp (10g) baking soda
  • 1 tsp (5g) baking powder
  • 1 tsp (6g) salt
  • 1 cup (240ml) buttermilk
  • 1/2 cup (120ml) vegetable oil
  • 2 large eggs
  • 2 tsp (10ml) vanilla extract
  • 1 cup (240ml) boiling water
  • 1/2 cup (115g) unsalted butter, melted
  • 2/3 cup (60g) unsweetened cocoa powder
  • 3 cups (360g) powdered sugar
  • 1/3 cup (80ml) whole milk
  • 1 tsp (5ml) vanilla extract

Instructions:

  1. Preheat oven to 350°F (175°C). Grease a 9x13 inch baking pan or line it with parchment paper.
  2. In a large mixing bowl, whisk together all-purpose flour, granulated sugar, 75g cocoa powder, baking soda, baking powder, and salt until combined.
  3. Add buttermilk, vegetable oil, eggs, and 10ml vanilla extract to the dry ingredients. Whisk until smooth.
  4. Stir in the boiling water by hand until the batter is thin and smooth.
  5. Pour batter into the prepared pan and bake for 20–30 minutes, or until the edges pull away from the pan and a toothpick inserted into the center comes out with a few moist crumbs.
  6. Cool the cake completely on a wire rack.
  7. Prepare frosting by whisking melted butter and 60g cocoa powder together, then gradually adding powdered sugar and milk until glossy and spreadable. Stir in 5ml vanilla extract.
  8. Smooth the frosting over the top of the cooled cake.