Ingredients:

  • 1 ½ cups (192g) all-purpose flour
  • ½ cup (50g) unsweetened cocoa powder
  • 1 ½ teaspoons baking soda
  • ½ teaspoon baking powder
  • ½ teaspoon salt
  • 1 cup (226g) unsalted butter, softened
  • 1 ¾ cups (350g) granulated sugar
  • 2 large eggs
  • 1 teaspoon vanilla extract
  • 1 cup (240ml) buttermilk
  • 1 cup (240ml) boiling water
  • 2 teaspoons instant espresso powder (optional)
  • ½ cup (113g) unsalted butter (for glaze)
  • 4 tablespoons milk (for glaze)
  • 4 tablespoons (20g) unsweetened cocoa powder (for glaze)
  • 3 cups (360g) powdered sugar, sifted (for glaze)
  • ½ teaspoon vanilla extract (for glaze)

Instructions:

  1. Preheat oven to 350°F (175°C). Grease and flour a 9x13 inch baking sheet.
  2. Whisk together flour, cocoa powder, baking soda, baking powder, and salt in a large bowl.
  3. Cream softened butter and sugar together until light and fluffy.
  4. Beat in eggs one at a time, then stir in vanilla extract.
  5. Gradually add the dry ingredients to the wet ingredients, alternating with the buttermilk, beginning and ending with the dry ingredients.
  6. Stir the instant espresso powder into the boiling water, then add to the batter. Mix until just combined.
  7. Pour batter into prepared baking sheet and spread evenly. Bake for 25-30 minutes, or until a wooden skewer inserted into the center comes out clean.
  8. Let the cake cool completely on a wire rack.
  9. In a saucepan, melt butter, milk, and cocoa powder over medium heat, stirring constantly.
  10. Remove from heat and whisk in powdered sugar and vanilla extract until smooth.
  11. Pour glaze over cooled cake and spread evenly. Let the glaze set before cutting and serving.