Prepare an 8x8 inch pan by lining it with parchment paper and set aside.
Preheat the oven to 350 degrees F.
In a medium size mixing bowl add the melted butter, white and light brown sugar. Stir to combine this together.
Stir in the egg and vanilla until smooth.
Add the flour, cornstarch, baking soda, and salt. Stir until dough forms.
Stir in the chocolate chips.
Spread the dough in the prepared baking pan and smooth out the top.
Bake in the oven for 25 minutes or until the bars are golden on the top and lightly browning on the edges.
Remove from the oven, allow the bars to cool in the pan for 10 minutes, then using the parchment paper, pull from the pan and set on a wire rack to continue cooling.
Allow bars to cool before slicing.