Start by cubing cold unsalted butter and placing it in a mixing bowl. Cream the butter with both brown sugar and granulated sugar on medium speed for 4–5 minutes until the mixture is light and fluffy.

With the mixture still running, add the cold large eggs one at a time, fully incorporating each egg before adding the next.

In a separate bowl, whisk together the all-purpose flour, cornstarch, baking powder, baking soda, and salt. Ensure there are no lumps.

Gradually add the dry ingredient mixture to the creamed butter and sugar mixture, mixing on low speed until a thick cookie dough forms.

Using a spatula, gently fold in the semi-sweet and milk or white chocolate chips, plus any optional nuts if desired.

Divide your cookie dough into 8–10 equally-sized balls, weighing about 6 ounces each; place the dough balls on parchment-lined baking sheets.

For an extra boost in flavor, refrigerate the shaped dough balls for 30 minutes to 1 hour.

During the last 10 minutes of chilling, preheat your oven to 400°F (205°C).

Bake 3–4 dough balls on the prepared baking sheet for 9–11 minutes.

Let the cookies cool on the pan for around 10 minutes before transferring them to a wire rack.