Ingredients:

  • 3/4 cup unsalted butter, softened
  • 3/4 cup dark brown sugar, packed
  • 1/4 cup granulated sugar
  • 1 large egg
  • 1 large egg yolk
  • 1 tablespoon vanilla extract
  • 2 cups all-purpose flour
  • 2 teaspoons cornstarch
  • 1 teaspoon baking soda
  • 1/2 teaspoon kosher salt
  • 1 1/4 cups semi-sweet chocolate chips
  • 1/2 cup unsalted butter, softened (for frosting)
  • 1 1/2 cups powdered sugar
  • 1.5 tablespoons heavy cream
  • 1 teaspoon vanilla extract (for frosting)
  • 1 pinch salt

Instructions:

  1. In a large bowl or stand mixer, beat 3/4 cup softened butter, dark brown sugar, and granulated sugar on medium-high speed for 2-3 minutes until the texture is pale and aerated.
  2. Add the whole egg, the extra egg yolk, and 1 tablespoon of vanilla extract. Beat until the mixture is fully incorporated and velvety.
  3. Sift the all-purpose flour, cornstarch, baking soda, and 1/2 teaspoon kosher salt directly into the wet ingredients. Mix on low speed until just a few streaks of flour remain.
  4. Fold in the semi-sweet chocolate chips using a rubber spatula.
  5. Press the dough evenly into a greased 9-inch round cake pan or springform pan. Since this is a no-chill recipe, proceed immediately to baking.
  6. Bake at 350°F (175°C) for 20 minutes. The edges should be a deep mahogany color while the center remains slightly soft to the touch.
  7. Allow the cookie cake to cool completely in the pan before removing. This sets the internal structure.
  8. Prepare the buttercream by beating 1/2 cup butter, powdered sugar, heavy cream, vanilla, and a pinch of salt until light and fluffy. Pipe a decorative border using an Open Star 1M tip.