Heat the oven to 350 F and spray an 8×8-inch square pan with non-stick cooking spray. Line the pan with parchment paper, leaving a three inch overhang on either side of the pan, and spray the paper with non-stick cooking spray.
In the work bowl of a stand mixer, or in a medium bowl with a hand mixer, beat the butter, brown sugar, and sugar on low speed until well combined but not fluffy, about 1 minute. Add the egg and vanilla and mix until the mixture is smooth.
In a separate bowl sift together the flour, baking soda, and salt. Add the sifted dry ingredients into the butter mixture and beat on low speed until the flour is just combined, about 30 seconds, then add the chocolate chips and mix until the chips are well distributed, about 30 seconds more. Press the dough evenly into the prepared pan and set aside.
In the work bowl of a food processor combine the cream cheese, brown sugar, and cornstarch. Process until the brown sugar has completely dissolved, about 3 minutes, stopping occasionally to scrape down the sides of the bowl. Add the egg, sour cream, and vanilla and process until well combined, about 30 seconds.
Pour the cheesecake mixture over the top of the bars. Rap the pan lightly on the counter to release any air bubbles. Bake for 30 to 40 minutes, or until the cheesecake is firm at the edges but the center is still slightly wobbly. Remove the pan from the oven and cool completely to room temperature, then chill for 4 hours or overnight. Once chilled use the excess parchment to remove the cookie from the pan. Cut into 16 pieces.
Recipe by Evil Shenanigans at http://evilshenanigans.com/2012/11/butterscotch-cheesecake-topped-chocolate-chip-cookie-bars/