• Notes before beginning: The brownie cookie dough will need to chill for a minimum of 1 hour but can be made up to 2 days in advance of assembling and making the cookies. Note that the brownie batter is easiest to work with after an hour or two in the fridge. Longer than that and it is much more firm, but still quite possible to work with. The chocolate chip dough must be chilled for a minimum of 30 minutes and up to 2 days in advance as well.

Make the brownie batter first:

• In a medium-sized, microwave safe mixing bowl, combine the 10 oz chopped semisweet chocolate or chips and butter. Heat in 25-second intervals, stirring well in between, until chocolate and butter are completely melted and smooth. Set aside.
  10 oz (g) semisweet chocolate baking bar, ⅓ cup unsalted butter
• In a separate, large mixing bowl, combine sugar, eggs, vanilla extract, and salt. Begin to stir on low-speed and gradually increase speed to high. Continue to beat on high speed until mixture is foamy and lightened in color, about 2-3 minutes.
  1 ¼ cups (g) granulated sugar, 3 large eggs, 1 teaspoon vanilla extract, ¾ teaspoon table salt
• Add the melted chocolate mixture into the egg mixture and stir on low-speed until completely combined.
• Sift flour, cocoa powder, and baking powder over the egg mixture (or whisk this together in a separate bowl and then add it to the batter) and use a spatula to fold together until ingredients are completely combined. Add mini chocolate chips, if using.
  ⅔ cup (g) all-purpose flour, ⅓ cup natural cocoa powder, ¼ teaspoon baking powder, ⅔ cup (g) mini semisweet chocolate chips
• Cover the dough tightly with plastic wrap and transfer to the refrigerator to chill for at least 1 hour. Prepare the chocolate chip cookie dough.

Prepare the chocolate chip cookie dough:

• In a large mixing bowl using an electric mixer (or in the stand mixer fitted with the paddle attachment) combine butter and sugars and beat until well-creamed (about 3 minutes on high).
  1 cup (g) unsalted butter, 1 cup (g) light brown sugar, ½ cup (g) granulated sugar
• Add eggs, one at a time, and stir well after each addition.
  2 large eggs
• Stir in vanilla extract.
  1 Tablespoon vanilla extract
• In a separate, medium-sized mixing bowl, whisk together flour, cornstarch, baking powder, baking soda and salt.
  3 ⅔ cups (g) all-purpose flour, 1 Tablespoon cornstarch, 2 teaspoons baking powder, ½ teaspoon baking soda, 1 teaspoon table salt
• Gradually (in 4 parts), with mixer on low-speed, stir the dry ingredients into the wet until dough is uniform and well-combined (pause occasionally to scrape the sides and bottom of the bowl).
• Stir in chocolate chips.
  1 cup semisweet chocolate chips
• Cover dough tightly with plastic wrap and transfer to the refrigerator to chill for at least 30 minutes (and for up to 2 days), until ready to assemble and bake.

Assemble and Bake

• Once doughs have chilled completely, preheat oven to 350F (175C) and line several baking sheets with parchment paper. Set aside.
• Remove both doughs from the refrigerator.
• Scoop 2 Tablespoons (40g) of brownie cookie dough and 2 Tablespoons (40g) of chocolate chip cookie dough. Press the two doughs together and twist/swirl to form a blended dough ball (sometimes I form together, break in half, twist, and re-smash together the dough).
• Place cookie dough balls on the prepared baking sheet, spacing at least 2” (5cm) apart. Transfer to center rack of 350F (175C) preheated oven and bake for 13 minutes (edges should be set, the edges of the chocolate chip cookie dough should appear a light golden brown). If desired, sprinkle with flaky sea salt while warm.
  Flaky sea salt for topping
• Allow cookies to cool completely on baking sheet before removing and enjoying.