Preheat the oven to 350° F and line a 9x13 inch baking dish with parchment paper. You need to cut two pieces to line the pan.
In a large microwave safe bowl combine the ½ cup butter and 6 oz chocolate. Microwave for 30 seconds at a time stirring in between until the chocolate is completely melted. Up to 90 seconds total. Let the chocolate cool for 5 minutes.
Add 1 cup sugar, 3 eggs, and 1 teaspoon vanilla extract and whisk well to combine until frothy, about 1 minute.
Next add in the ½ cup flour, ¼ cup cocoa powder, and ½ teaspoon kosher salt. Whisk until combined.
Pour the batter into the pan and spread evenly around with the back of a spoon. Set aside to make the cookie dough.
In a medium sized microwave safe bowl melt the ½ cup butter. Add the ⅔ cup brown sugar and 2 tablespoon white sugar and mix till smooth.
Add the 2 egg yolks and 1 teaspoon vanilla extract and mix again.
Add in the 1 ¾ cups flour, ¼ teaspoon baking powder, ½ teaspoon baking soda, and ¼ teaspoon kosher salt and stir till dough forms.
Add in the 1 cup chocolate chips and mix well to ensure that the chips are sticking in the batter.
Using a small spoon, dollop small clumps of cookie dough on top of the brownie batter. It doesn’t have to be shaped into a ball.
Dollop all over the brownies using all the cookie dough.
Put the pan in the oven and bake for 30-35 minutes uncovered. Remove from the oven and let cool 15 minutes before cutting into them. This helps them keep their shape!