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 (5g) salt
  • 1 cup (240ml) buttermilk, room temperature
  • 1/2 cup (120ml) vegetable oil
  • 2 large eggs, room temperature
  • 1 tsp (5ml) vanilla extract
  • 1 cup (240ml) boiling water
  • 1/2 cup (115g) unsalted butter
  • 1/3 cup (30g) unsweetened cocoa powder

Instructions:

  1. Preheat oven to 350°F (175°C) and thoroughly grease a 9x13 inch baking pan with butter or cooking spray.
  2. Sift together the flour, sugar, cocoa powder, baking soda, baking powder, and salt into a large bowl and whisk until uniform in color.
  3. Add the buttermilk, oil, eggs, and vanilla to the dry ingredients. Whisk on medium speed for about 2 minutes until the batter is smooth and glossy.
  4. Carefully stir in the boiling water by hand until combined; the batter will be thin.
  5. Pour the batter into the prepared pan and smooth the top with a spatula.
  6. Bake on the center rack for 30-35 minutes.
  7. Perform the toothpick test: insert a toothpick into the center; it should come out with a few moist crumbs attached, but no raw batter.
  8. Melt the butter for the glaze in a saucepan over medium heat.
  9. Whisk the cocoa powder into the melted butter.