Ingredients:

  • 1½ cups all-purpose flour
  • ¾ cup granulated sugar
  • ¼ cup unsweetened cocoa powder
  • 1 tsp baking powder
  • ½ tsp baking soda
  • ¼ tsp salt
  • 1 cup whole milk
  • 2 tbsp melted unsalted butter
  • 1 large egg
  • 1 tsp vanilla extract
  • ½ cup unsweetened cocoa powder
  • ½ cup packed brown sugar
  • 1¼ cups boiling water

Instructions:

  1. Preheat the oven to 350°F (180°C) and lightly grease a 9x9 inch baking dish with butter or non-stick spray.
  2. In a large bowl, whisk together 1½ cups all-purpose flour, ¾ cup granulated sugar, ¼ cup unsweetened cocoa powder, 1 tsp baking powder, ½ tsp baking soda, and ¼ tsp salt until no lumps remain.
  3. Stir in 1 cup whole milk, 2 tbsp melted unsalted butter, 1 large egg, and 1 tsp vanilla extract, whisking until the batter is smooth and glossy.
  4. Pour the batter evenly into the prepared baking dish, smoothing the top with a spatula.
  5. In a small bowl, combine ½ cup unsweetened cocoa powder and ½ cup packed brown sugar.
  6. Sprinkle the cocoa-sugar mixture evenly over the top of the raw cake batter without stirring.
  7. Carefully pour 1¼ cups boiling water over the back of a spoon onto the cocoa layer to prevent digging into the batter; do not stir.
  8. Place the dish in the center of the oven and bake for 30–35 minutes until the top feels set to a light touch and the edges have slightly pulled away from the sides of the pan.
  9. Remove from the oven and let the cake stand for 10 minutes to allow the sauce to thicken into a velvety consistency.