Preheat oven to 350° Fahrenheit. Line 2 cookie sheets with parchment paper. In a medium bowl, combine flour, cornstarch, baking soda, ground cinnamon, and salt. Mix briefly with a fork to combine and set aside.
In a bowl of an electric mixer fitted with a paddle attachment (hand mixer and large bowl work here too), over medium/high speed, cream the butter and both sugars until light and fluffy, about 2-3 minutes. Add the eggs one at a time, beating well after each addition. Reduce the mixer speed to low and add the vanilla extract. Stop and scrape the mixer to incorporate ingredients.
Turn the mixer speed to low and add the flour mixer all at once. Mix until mostly combined, about 20-25 seconds. It’s fine if you see some flour bits. Remove bowl from the mixer and fold in the chocolate chips and walnuts.
With a ½ cup measuring cup, scoop out portions of cookie dough and very quickly roll them into balls. This batter should make 8 large cookies.
Place four cookies very far apart on each baking sheet. Place trays in the oven and baked for 12-14 minutes. The tops would have lost their shine and the edges will look lightly browned.
Remove from the oven and allow the cookies to cool on the cookie sheets for about 5-10 minutes.