1. Preheat oven to 350F/180C and line a 9X9 inch pan with parchment paper and grease the pan thoroughly, set aside.
2. In the bowl of an electric stand mixer fitted with the paddle attachment or a large mixing bowl with a handheld electric mixer mix together the butter and sugars for 2 minutes., until light and fluffy. Add in the first egg and vanilla extract, mix to combine then add in the second egg. Make sure to scrape down the sides of the bowl so everything is combined.
3. Mix in baking soda, salt, and flour until no flour steaks remain. Fold in chocolate chips. Press half of the dough into the prepared pan.

Cheesecake Layer

1. In the bowl of an electric stand mixer fitted with the paddle attachment or a large mixing bowl with a handheld electric mixer beat the cream cheese for 2 minutes on medium speed. Add in sugar beating for another minute. Add in egg and vanilla extract and beat on low speed for a minute or so until there is no trace of egg yolk left behind.  Pour on top of cookie dough layer. Take chunks of  the remaining cookie dough and sort of flatten into discs between your hands and layer on top of the cheesecake layer. Add extra chocolate chips on top if desired.
2. Bake in preheated oven for 35-45 minutes, the cookie dough should be golden brown and set. If you jiggle the baking tray the center should slightly wobble but be set, if the center moves a lot then the bars are not done and need more baking time.  Let cool at room temperature for an hour or so then cover and chill in the fridge for a few hours before slicing. Store leftovers in the refrigerator.