Prepare brownie according to package directions. Let cool completely then cut into 1 1/2 inch squares.
In a stand or electric mixer, beat the butter and sugars until light and fluffy.
Add eggs and vanilla, continue to beat until well combined.
Place flour, salt and baking soda into a bowl; mix to combine then add slowly to wet ingredients along with the chocolate chips.
Place a large cookie scoopful of dough on top of a brownie square and another large scoop on the bottom. Gently press and enclose brownie with dough adding pinches more dough to cover sides if needed.
Place 6 filled cookies onto a parchment or silpat lined baking sheet and bake for 18-22 minutes or until edges are golden brown. Remove and let cool for 15 minutes before removing from baking sheet.