Ingredients
Method
Instructions
- Preheat your oven to 350°F (175°C). Grease and flour a 10x15-inch jelly roll pan or line it with parchment paper.
- In a large mixing bowl, whisk together the flour, sugar, baking soda, and salt until well combined.
- In a medium saucepan, combine the butter, water, and cocoa powder. Heat over medium heat, stirring constantly, until the butter melts and the mixture comes to a gentle boil.
- Pour the hot chocolate mixture over the dry ingredients and stir until just combined.
- In a small bowl, whisk together the eggs, buttermilk, and vanilla extract. Add this to the batter and mix until smooth and well combined.
- Pour the batter into the prepared pan and spread it evenly. Bake for 20-25 minutes, or until a toothpick inserted into the center comes out clean.
- While the cake is baking, prepare the icing. In a medium saucepan, combine the butter, cocoa powder, and buttermilk. Bring to a boil, then remove from heat. Whisk in the powdered sugar and vanilla until smooth. Stir in nuts if using.
- As soon as the cake comes out of the oven, pour the warm icing over the hot cake. Spread it evenly with a spatula. Allow the cake to cool completely before cutting into squares.
Notes
Buttermilk is essential for signature tang and tender crumb; pour warm icing over hot cake for perfect melt-in texture; don't overmix the batter; let cake cool completely before cutting for clean slices.
