First start by preheating your oven to 375F, then line your baking sheet with parchment paper or a silicone mat.
Cream the butter with the brown sugar and the granulated sugar with a paddle attachment or with a hand mixer until smooth. This will take 3-4 minutes. Scrape the bowl as needed.
Add in the room temperature eggs and vanilla, mixing on low speed until fully incorporated. Continue mixing for about 2-3 minutes until the batter is nice and smooth. Keep scraping the sides of the bowl as necessary.
Turn the mixer to low speed and add in the the flour, corn starch, baking soda, and salt and mix just until combined! DO NOT OVER MIX!
With the mixer still on low, add in the two types of chocolate chips and the walnuts and mix just until combined. If you are using a hand mixer, stop and fold them using a spatula. You do not want to break your mixer!
Using a large cookie scoop, scoop out 13 equal cookie dough balls and place them on the baking sheet about 2 inches apart. Place the cookies in the freezer for 10 minutes, then bake at 375F for 15 minutes.
Allow the cookie to cool on the baking sheet for 10 minutes and then transfer to a cooling rack. Enjoy these cookies either warm with a cup of milk or cold with a cup of hot tea!