For the Brownie Cookies

1. Preheat your oven to 350 degrees Fahrenheit. Line baking sheets with parchment paper to ensure the cookies come off of the pans cleanly after baking.
2. In a medium bowl, whisk all purpose flour, baking soda, and salt together.
3. In a large bowl, whisk cocoa powder and warm melted butter together. The mixture will have a paste-like consistency.
4. Mix light brown sugar, granulated sugar, room temperature egg, room temperature egg yolk, and vanilla extract into the butter and cocoa powder mixture. Whisk until smooth.
5. Carefully, whisk dry ingredients into the rest of the batter. Do not overmix, as doing so could impact the texture of the cookies. Mix only until you see the dry ingredients disappear into the dough.
6. Let the batter rest as you prepare the chocolate chip cookie dough batter.

For the Chocolate Chip Cookies

1. In a medium bowl, whisk all purpose flour, corn starch, baking soda, and salt together.
2. In a large bowl with a hand mixer or in the bowl of a stand mixer that is fitted with a paddle attachment (preferred), beat room temperature butter, light brown sugar, and granulated sugar together on high speed until slightly pale in color, puffy in texture, and shiny.
3. Add egg and vanilla extract to the batter and mix on medium speed until smooth. Scrape down the sides and the bottom of the bowl as necessary to ensure the ingredients are dispersed evenly throughout the batter.
4. Slowly, add the dry ingredients to the batter on low speed to prevent the dry ingredients from spilling out of the bowl. Mix only until you see the dry ingredients disappear into the batter.
5. Add chocolate chips to the dough and mix until dispersed throughout the batter.

For Assembly & Baking

1. Divide the brownie cookie batter into slightly smaller than 1 tablespoon balls, about 25-30g of batter.
2. Divide the chocolate chip cookie dough batter into slightly larger than 1 tablespoon balls, about 30-35g of batter.
3. Place one of each dough ball next to each other before squishing the two together and rolling them into one smooth ball.
4. As recommended in “Expert Tips & Tricks” above, stick additional chocolate chips into the tops of the dough ball as desired. Repeat the rolling and decorating process for the remaining dough balls.
5. Place the cookies at least 2 inches apart on a baking sheet, as the cookies will spread and rise as they bake.
6. Bake cookies for 9-11 minutes or until the chocolate chip cookie portion is light golden brown on top, the cookies look slightly shiny on top and soft in the middle, and the bottom of the chocolate chip cookie portion looks golden brown when carefully lifted off of the baking sheet with a spatula.
7. Allow the cookies to cool on the pan for about 5 minutes until they are firm enough to transfer to a wire cooling rack or cool plate. If you have overbaked the cookies, carefully remove them from the pan immediately after removing the pan from the oven to ensure the cookies do not bake for any longer.
8. Store at room temperature tightly covered or in an airtight container for up to 4 days after they have completely cooled. Cookies can be frozen in a freezer bag, individually wrapped, or in an airtight container for up to 3 months.