First make the chocolate chip cookie dough. It must chill while you prepare the brownie dough.
In a medium sized bowl whisk together the flour, baking soda, and sea salt; set aside.
In a large bowl using a handheld electric mixer, or in a stand mixer, beat the butter on medium speed until smooth. Add the sugars and vanilla and beat on medium speed until the mixture is pale and fluffy; about 2 minutes.
Add in the egg and beat. Gently fold in the flour mixture with a rubber spatula, stirring only until the flour begins to disappear. Fold in the chocolate chips.
Cover the bowl with plastic wrap and place it in the fridge for 30-45 minutes.
Brownie Cookie Dough
Place the butter and chocolate in a small sauce pan over medium heat and cook for about 2 minutes- stirring constantly- or until butter and chocolate are completely melted. Remove from heat and whisk until completely smooth; set aside.
In a medium sized bowl whisk together the flour, cocoa powder, baking soda, and salt; set aside.
Add the sugars and the vanilla to the chocolate mixture and whisk until well combined; about 2 minutes. I always use a hand mixer. Add in the egg and egg yolk and beat well. Gently fold in the flour mixture with a spatula, stirring only until the flour disappears. Fold in the chocolate chips.
Putting it all together.
Preheat oven to 350 degrees. Line 2 large baking sheets with parchment paper and set aside.
Using a cookie scoop (I used 2 tablespoon size), scoop the cookie dough onto the parchment paper allowing 2 inches between each scoop.
Then scoop the brownie cookie dough directly next to each ball of chocolate chip cookie dough.
Join the two cookie doughs by gently pinching them together, be sure to adhere any gaps.
Place baking sheets in preheated oven and bake for 12 minutes, or until the edges and tops are set but the centers still look slightly underdone. Let cookies cool for 10 minutes on the baking sheet before transferring them to a wire rack to cool.
Recipe Notes
Recipe: Baker by Nature: Chocolate Chip Brownie Swirl Cookies