Ingredients:

  • 1 box (15.25 oz / 432 g) yellow cake mix
  • 1/2 cup (115 g) unsalted butter, melted
  • 2 large eggs
  • 1 cup (170 g) semi-sweet chocolate chips
  • 1 tsp (5 ml) vanilla extract

Instructions:

  1. Preheat the oven to 350°F (175°C). Grease a 9x13 inch rectangular pan with non-stick spray or line it with parchment paper, leaving an overhang on the sides.
  2. In a large mixing bowl, combine melted butter and eggs. Whisk vigorously until the mixture is smooth and pale. Stir in the vanilla extract.
  3. Slowly add the yellow cake mix to the butter and egg mixture, beating on medium speed until the batter is thick and cohesive, stopping as soon as no dry streaks of flour remain.
  4. Using a spatula, gently fold in the semi-sweet chocolate chips until evenly distributed.
  5. Press the dough into the prepared pan and smooth the top with the back of a spoon.
  6. Bake for 18–22 minutes until the edges are deep golden brown and pulling away from the sides, while the center remains slightly under-set.