Preheat oven to 325 degrees F.
Line an 8x8 or 9x9 inch baking pan with parchment paper, in a way so it has handles on two of the sides, for easy bars removal.
Add flour, salt, baking soda, baking powder, and cornstarch to a medium bowl and whisk to combine, set aside.
Add the melted butter to a large bowl, and add the sugars, whisk together, until well combined.
Add the eggs and vanilla to the butter mixture and mix together well.
Add the dry mixture into the wet and mix until just combined, then using a spatula, stir in the chocolate chips, leaving out 1/4 cup.
Transfer the dough to the prepared baking dish and smooth the top. Top with the reserved 1/4 cup of chocolate chips.
Bake for about 35-40 minutes, the edges should be set and golden brown and a toothpick inserted into the center comes out mostly clean. If the dessert starts to brown really quickly, cover loosely with parchment paper.
Let the cookie bars cool in the pan for about 10 minutes, lift and transfer to the counter to cool completely before cutting.