Bake brownies in a 9 x 13 pan according to directions on back of box.
Cool brownies and cut out two 6 inch circles.
Place one circle of brownie into a 6" springform pan. Layer with one pint of ice cream
Repeat with second circle of brownie and remaining ice cream
Cover with plastic wrap and return to freezer to harden.
Remove from freezer 5 minutes before serving and allow to soften a bit.
Top with hot fudge and pieces of the remaining brownies.
Video
Notes
If you don't have a springform pan, you can use a regular 6 inch round cake pan but line it with parchment paper or wax paper to make it easier to remove the cake for serving.To make a bigger cake , use an 8 inch springform pan. You will need to use two brownie mixes and 2 quarts of ice cream and additional hot fudge sauce.