Chocolate Chip Brownie Swirl Cookies

Ingredients
For the Chocolate Chip Cookie:
1 and 1/4 cups all-purpose flour
1/2 teaspoon baking soda
1/4 teaspoon flaky sea salt (regular salt will work in a pinch)
7 tablespoons unsalted butter, at room temperature
1/2 cup packed dark brown sugar
1/4 cup granulated sugar
1 teaspoon vanilla
1 large egg
3/4 cup semi-sweet chocolate chips
For the Brownie Cookie:
6 tablespoons unsalted butter, melted
1/2 cup semi-sweet chocolate chips, melted
1 cup all-purpose flour
2 tablespoons unsweetened cocoa powder
1/2 teaspoon baking soda
1/4 teaspoon salt
1/2 cup packed dark brown sugar
1/4 cup granulated sugar
1 teaspoon pure vanilla extract
1 large egg + 1 egg yolk, at room temperature
3/4 cup milk chocolate chips

Instructions

For the Chocolate Chip Cookie:
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 the bowl of a stand mixer fitted with the paddle attachment, beat the *room temperature butter on medium-speed until smooth. Add in 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 well after its addition. Gently fold in the flour mixture with a rubber spatula, stirring only until the flour begins to disappear. Fold in chocolate chips.
Cover the bowl with plastic wrap and place it in the fridge for 45 minutes (set a timer!).
For the Brownie Cookie:
Place butter and chocolate in a small sauce pan over medium heat and cook for about 2 minutes – stirring constantly – or until the 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 recommend using a stand mixer/ handheld mixer to do this, if you have one). Add in the egg and egg yolk and beat well. Gently fold in the flour mixture with a rubber spatula, stirring only until the flour begins to disappear. Fold in chocolate chips.
Assembly and Baking:
Preheat oven to 350 degrees (F). Line 2 large baking sheets with parchment paper and set aside.
Using an ice cream scoop or tablespoon, scoop 2 tablespoon-sized rounds of chocolate chip cookie dough onto the prepared baking sheets, leaving 2 inches in between each cookie for spreading.
Use a second measuring device (ice cream scoop or tablespoon) to scoop rounds of brownie cookie dough directly next to each round of chocolate chip cookie dough.
Join the two cookie doughs by gently pinching them together, being 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 looks slightly underdone. Let cookies cool for 10 minutes on the baking sheet before transferring them to a wire wrack to cool completely.