Start by cubing cold unsalted butter into small pieces and adding it to your mixing bowl. Cream the butter with both brown and granulated sugars using an electric mixer on medium speed for 3–5 minutes, until the mixture turns light and fluffy.

Next, add two room-temperature eggs and a splash of vanilla extract to the creamed mixture. Beat the ingredients together until fully combined.

In a separate bowl, whisk together baking soda, salt, cornstarch, and 1 cup of all-purpose flour. Gradually add this dry mixture into the wet ingredients while mixing on low speed.

Fold in the milk chocolate and semi-sweet chocolate chips gently with a spatula. If you're adding nuts, mix in walnuts or pecans for additional texture.

Using a large ice cream scoop or your hands, scoop tall mounds of dough and shape them into oval-like forms. Chill the cookie dough in the refrigerator for a minimum of 2 hours.

Preheat your oven to 350°F (175°C) while the dough chills. Bake the cookies for 13-15 minutes, watching closely.

After baking, remove the cookies from the oven and let them rest on the baking sheet for 3-5 minutes before transferring to a cooling rack.