Preheat your oven to 325℉ and line a 9x9 baking dish with parchment paper.
Make brownies according to directions on the box and let cool completely.
Take a flat spatula and press down the brownie layer to make it more compact.
Take ice cream out of freezer while you make the cookie dough to thaw slightly.
In the bowl of a stand mixer or using a hand mixer, cream together butter and both sugars until light and fluffy.
Add flour, salt and vanilla and mix to combine.
Add chocolate chips and fold in with a spatula.
Roll out cookie dough between two sheets of parchment paper into a rough 9x9 square for easy transfer.
Scoop slightly melted ice cream on top of the cooled brownie layer and smooth with a spatula.
Take off one side of the parchment paper off of the cookie dough layer and carefully flip upside down onto the ice cream layer and peel off the other side of parchment. .
Patch up any place that is not covered by cookie dough and return to the freezer until fully set. About 4-5 hours minimum.
Take ice cream sandwiches out of the dish by lifting the parchment paper and cut into bars.
ENJOY!!