1-Toast walnuts at 350°F for 8-10 minutes,: Toast walnuts at 350°F for 8-10 minutes, cool and chop.
2-Cream butter and sugars until light and: Cream butter and sugars until light and fluffy.
3-Add egg, egg yolk, and vanilla: Add egg, egg yolk, and vanilla. Beat to combine.
4-In a separate bowl, whisk flour, cornstarch,: In a separate bowl, whisk flour, cornstarch, baking soda, and salt.
5-Add dry ingredients to wet and mix: Add dry ingredients to wet and mix until a soft dough forms.
6-Fold in chocolate chips and walnuts: Fold in chocolate chips and walnuts.
7-Scoop dough into balls and chill for: Scoop dough into balls and chill for 30 minutes.
8-Preheat oven to 350°F: Preheat oven to 350°F. Line trays with parchment.
9-Bake cookies for 11-13 minutes until edges: Bake cookies for 11-13 minutes until edges are golden.
10-Cool 5 minutes on tray, then transfer: Cool 5 minutes on tray, then transfer to wire rack.