1(16-ounce) box brownie mix, prepared according to package
Flakey sea salt, optional
Instructions
Preheat oven to 350℉. Line a 9x13-inch, light-colored metal baking pan with parchment paper and lightly spray the bottom with cooking spray.
In a medium bowl, beat together the butter, granulated sugar, and brown sugar with a handheld mixer until fluffy. Mix in the egg and vanilla extract until combined.
In a small bowl, whisk together the flour, baking soda, and salt.
Using a wooden spoon, stir together the flour mixture to the wet ingredients just until combined. Stir in 1/2 cup chocolate chips. Cover and refrigerate the cookie dough while preparing the brownie batter.
Prepare the brownie batter according to the instructions up until baking.
Spread the brownie batter into the pan. Using your hands, drop the chilled cookie dough by spoonfuls across the top of the brownie layer. It is okay to see the brownie layer, as it will create a marbled look. Very lightly press the dollops of cookie dough (just enough to settle it into the brownie layer). Sprinkle remaining 1/4 cup chocolate chips on top.
Bake 25 to 30 minutes, or until a toothpick comes clean. If the cookie layer is browning too quickly you can loosely cover the pan with aluminum foil.
Sprinkle with flakey sea salt, if using, and cool fully before cutting in. Serve bars alone or with a scoop of ice cream!