Preheat the oven to 350°F and line a 9×13-inch baking pan with parchment paper or coat it with non-stick spray.
In a large bowl, use a hand mixer to combine the chocolate chip cookie mix, butter, and egg until smooth.
Press the dough evenly into the bottom of the prepared pan.
Arrange the Oreos evenly on top of the cookie dough.
In another bowl, beat the cream cheese, powdered sugar, and cornstarch until light and fluffy.
Blend in the sour cream until smooth.
Add the eggs one at a time, mixing briefly after each addition.
Fold in ⅔ cup of chopped Oreos.
Spread the cheesecake mixture evenly over the Oreos in the pan.
Sprinkle the remaining ⅔ cup of chopped Oreos on top.
Bake for 35-40 minutes, or until the cheesecake layer is set and reaches around 150°F.
Allow the bars to cool to room temperature on a wire rack.
Cover the pan with plastic wrap and refrigerate for at least 3 hours or until completely chilled.
Before serving, cut into squares and drizzle with caramel sauce if desired.