Ingredients:

  • 1 cup unsalted butter
  • 1 cup water
  • 0.25 cup unsweetened cocoa powder
  • 2 cups all-purpose flour
  • 2 cups granulated sugar
  • 1 tsp baking soda
  • 0.5 tsp salt
  • 2 large eggs
  • 0.5 cup buttermilk
  • 1 tsp vanilla extract
  • 0.5 cup unsalted butter (for frosting)
  • 6 tbsp whole milk
  • 0.25 cup unsweetened cocoa powder (for frosting)
  • 4 cups powdered sugar
  • 1 tsp vanilla extract (for frosting)
  • 1 cup chopped pecans

Instructions:

  1. Preheat your oven to 400°F (200°C) and grease an 18x13 inch jelly roll pan.
  2. In a large saucepan, combine 1 cup butter, 1 cup water, and 1/4 cup cocoa powder. Bring to a rolling boil, whisking constantly until glossy, then remove from heat.
  3. In a separate large bowl, whisk together the flour, granulated sugar, baking soda, and salt. Pour the hot chocolate mixture over the dry ingredients and whisk until combined.
  4. In a small bowl, lightly beat the eggs with the buttermilk and 1 tsp vanilla. Stir this into the chocolate batter until smooth.
  5. Pour the batter into the prepared jelly roll pan and bake for 20 minutes, or until a toothpick comes out clean.
  6. While the cake is baking, prepare the frosting: In a saucepan, bring 1/2 cup butter, 6 tbsp milk, and 1/4 cup cocoa powder to a boil.
  7. Remove frosting base from heat and whisk in the powdered sugar and 1 tsp vanilla until smooth. Stir in the pecans if using.
  8. Pour the warm frosting over the cake immediately after removing it from the oven. Let cool completely before slicing.