Preheat the oven to 325°F and grease an 8x8 or 9x9 inch baking pan. Or you can line with parchment paper.
Make the cookie dough first. In a large bowl, whisk together the all-purpose flour, cornstarch, baking soda, baking powder and salt. Set aside.
2 cups all-purpose flour, 1 tsp. cornstarch, 1/2 tsp. baking soda, 1/2 tsp. baking powder, 1/2 tsp. salt
Cream the butter and sugars in a stand mixer using the paddle attachment until light and fluffy, ~2-3 minutes.
8 Tbsp. unsalted butter, cold, cut into cubes, 1/2 cup brown sugar, packed (light or brown), 1/4 cup granulated white sugar
Add in the egg, egg yolk and vanilla extract and mix again.
1 large egg, 1 large egg yolk (no white), 1 tsp. vanilla extract
Gradually add in the dry ingredients.
Add in chocolate chips just until combined. Set cookie dough aside.
2 cups chocolate chips
Make the cheesecake filling: using a hand mixer, beat the cream cheese and sugar until light and fluffy. Add in the egg, vanilla and flour and mix again until incorporated and smooth.
8 oz. cream cheese, softened, 1/2 cup granulated white sugar, 1 large egg, 1 Tbsp. flour, 1 tsp. vanilla extract
With lightly floured fingers, press ~2/3 of the cookie dough down onto the bottom of the prepared pan.
Pour the cheesecake filling over the crust in an even layer.
Take remaining cookie dough, flatten into discs and place on top of cheesecake layer. Repeat until cheesecake layer is mostly covered with cookie dough (there will be some gaps, that's OK).
Bake for ~35-40 minutes* or until cheesecake layer appears set. Cool at least 1 hour at room temperature before cutting into bars. You can also chill the bars before cutting to ensure clean cuts.
When ready to serve, cut into small squares and enjoy! Store in an air-tight container in the fridge.