Make the brownie batter as directed on the package and place all but ¼th of a cup in a greased 8x8" baking dish. (save that extra batter for later)
In a medium sized bowl, beat together the cream cheese, egg, sour cream, sugar, vanilla and salt until smooth.
Add the cheesecake mixture to the top of the brownies.
Randomly dollop the remaining brownie batter on top of the cheesecake layer.
Using a knife or a toothpick, swirl the cheesecake and dolloped brownie batter together.
Place it into the center rack of the oven for 35 minutes.
Let the brownies cool completely then place them into the fridge to set for at least 4 hours.
Finally, cut into individual portions and enjoy!