Remove from heat and allow to cool slightly before stirring in the brown sugar and granulated sugar, followed by the eggs and vanilla extract; set aside.
Pour the chocolate mixture into the flour mixture, then stir until just combined. Fold in the chocolate chips, then wrap the bowl with plastic wrap and refrigerate for 4 hours.
In the bowl of a stand mixer fitted with the paddle attachment, beat together the butter, brown sugar and granulated sugar until light and fluffy. Add the egg and vanilla and mix well.
Get a heaping tablespoon scoop of the brownie cookie dough, and a heaping tablespoon scoop of the chocolate chip cookie dough and press them together, then roll between your hands to create one large cookie dough ball
Place the cookie dough balls onto the prepared baking sheet 3” apart and press down slightly to flatten. Bake in the preheated oven for 9-11 minutes, or until the cookies are just golden on the edges.