Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

In a large mixing bowl, cream together the softened butter, granulated sugar, and brown sugar until light and fluffy.

Add the eggs one at a time, mixing well after each addition, then stir in the vanilla extract.

In a separate bowl, whisk together the flour, baking soda, and salt. Gradually add the dry ingredients to the wet mixture, mixing until just combined.

Fold in the chocolate chips and brownie mix until evenly distributed throughout the dough.

Using a tablespoon or cookie scoop, drop rounded balls of dough onto the prepared baking sheet, leaving about 2 inches between each cookie.

Bake in the preheated oven for 10-12 minutes, or until the edges are lightly golden. The centers may look slightly underbaked; they will continue to cook as they cool.

Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.