Make brownies according to box directions. After brownies have cooled, cut into small cubes.
Preheat the oven to 375°F and line baking sheets with parchment paper or silpat mats.
Whisk together flour, baking soda and salt in a medium sized bowl.
In a separate bowl cream the butter, sugar and brown sugar using an electric mixer until light and fluffy (about 2-3 minutes). Add the eggs and the vanilla and mix on medium speed until combined.
Add in the flour mixture on low speed until combined. Using a large spoon, mix in the chocolate chips.
Scoop a large tablespoon of dough and push a few chunks of brownies into the dough (I put about four on the surface and one inside) and drop onto baking sheet. Repeat until all dough is used up.
Bake for about 8-10 minutes. Remove cookies from tray and let them cool on wire racks.
The nutrition information provided are only estimates based on an online nutritional calculator. This is not a comprehensive list of all the nutrients in the recipe (i.e., does not include vitamins, cholesterol, etc). I am not a certified nutritionist. Please consult a nutritionist or doctor for accurate information and any dietary restrictions and concerns you may have.