Ingredients:

  • 3/4 cup (1.5 sticks) unsalted butter
  • 4 ounces high-quality dark chocolate (60-70% cacao), chopped
  • 2 cups granulated sugar
  • 3 large eggs
  • 3/4 cup all-purpose flour
  • 1 teaspoon vanilla extract
  • 1 teaspoon kosher salt

Instructions:

  1. Preheat oven to 350°F (175°C). Line an 8x8 inch baking pan with parchment paper, leaving an overhang on two sides. In a medium, heat-safe bowl, melt the butter and dark chocolate together over a double boiler or in the microwave until completely smooth. Let cool slightly (about 5 minutes).
  2. In a separate large bowl, combine the granulated sugar and eggs. Vigorously whisk together for 3 to 5 minutes until the mixture is thick, pale, and foamy. Add the vanilla extract and whisk briefly. This step is critical for developing the signature crinkle top.
  3. Gently fold the cooled chocolate mixture into the whipped egg mixture until just combined.
  4. In a small bowl, whisk together the flour and salt. Gently fold the dry ingredients into the wet mixture using a spatula, mixing only until the flour streaks disappear. Do not overmix, as this develops gluten and compromises the fudgy texture.
  5. Pour the batter into the prepared 8x8 pan. Bake for 28 to 32 minutes, or until the edges look set and a toothpick inserted in the center comes out slightly gooey but not wet. Let cool completely in the pan on a wire rack before lifting out and slicing into 16 squares.