Levain Bakery-style chocolate chip walnut cookies

Preheat the oven to 410F.

Cream the brown and white sugars with the cold cubed butter.

Add the eggs one at a time, then the cornstarch, salt and baking soda, then the cake flour and all-purpose flour; mix until just combined without overmixing.

Add two cups of chocolate chips and the chopped walnuts (some dough set aside without walnuts).

Scoop and shape into round balls, not packed too tightly, on a parchment-lined baking dish.

Bake one test cookie 9 to 12 minutes until golden on top, then bake the rest, on the bottom rack so the outside does not cook before the inside.