Step 1: Preheat oven to 350°F (175°C). Line a 9x9-inch square baking pan with parchment paper or aluminum foil, leaving overhang, and spray with nonstick spray.
Step 2: In a medium bowl, whisk together flour, baking soda, and salt.
Step 3: In a large bowl, cream together softened butter, brown sugar, and granulated sugar until light and fluffy.
Step 4: Add the egg and 2 tsp vanilla extract to the creamed butter mixture and beat until well combined.
Step 5: Gradually add the dry flour mixture to the wet ingredients. Mix on low speed or stir by hand just until flour is almost completely incorporated. Don't overmix.
Step 6: Fold the chocolate chips into the dough.
Step 7: Take about two-thirds of the cookie dough mixture and press it firmly and evenly into the bottom of the prepared pan.
Step 8: In a separate bowl, combine softened cream cheese, ½ cup sugar, the second egg, and 1 tsp vanilla extract. Beat until smooth and completely blended.
Step 9: Carefully pour or spread the cheesecake filling evenly over the cookie dough layer in the pan.
Step 10: Crumble the remaining one-third of cookie dough evenly over the top of the cheesecake filling.
Step 11: Bake for about 40 minutes, or until the cheesecake layer looks set (slightly jiggly in the center) and the cookie topping is golden brown.
Step 12: Let the bars cool completely in the pan on a wire rack. Cover the pan and chill in the refrigerator for at least 2-3 hours, or ideally longer, before slicing.
Step 13: Once chilled, use the overhang to lift the bars out. Slice into squares using a sharp knife (wipe knife clean between cuts for neat edges).
Step 14: Serve and enjoy!