Preheat oven to 325°F . Line a 9x9 metal pan with parchment paper, leaving an overhang on the sides for easy removal
Prepare the Ghirardelli brownie mix according to the box instructions. Set aside.
In a medium bowl, cream together softened butter and both sugars until light and fluffy (about 2 minutes). Beat in egg and vanilla.Add flour, baking soda, and salt and mix until just combined. Fold in chocolate chips.
Pour and spread the brownie batter evenly into the prepared pan. Dollop the cookie dough over the brownie layer in small scoops (like a patchwork quilt), then gently spread and flatten with your fingers or an offset spatula to cover most of the surface. It’s okay if a bit of brownie peeks through—it’ll swirl in the oven!
Bake for 35–40 minutes or until the cookie top is golden brown and a toothpick inserted in the center comes out with a few moist crumbs. If the top starts to brown too quickly, loosely tent with foil around the 30-minute mark.