Begin by toasting walnuts. Spread walnuts in an even layer in a small baking dish or pie tin and toast for 7 - 10 minutes at 350 or until nuts are fragrant. Once you smell them, they should be done. Do not let them burn! Cool.

Beat butter and both sugars together on medium speed in a stand mixer until creamy and fluffy-about 5 minutes. Add vanilla and egg and beat on medium high for about one minute.

Combine flour, cornstarch, baking soda and salt in a large mixing cup. Aerate with a fork and then add to mixing bowl. Stir in a bit so that when you turn the mixer on the flour doesn't go flying everywhere. OR cover mixing bowl with a clean dish towel while slowly mixing flour in until it blends into the mixture.

Stir in cooled walnuts and chocolate chips, but do not overmix.

Chill the dough for at least one hour and even up to two days.

When ready to bake, preheat the oven to 350. Line two baking sheets with parchment paper or use a silicon mat. Divide dough into 10 equal sized portions, of about 1/4 c each. (I made smaller cookies of about 2 T each.)

Bake the large cookies for 11-13 minutes. Do not overbake.

Let the cookies cool for 10 minutes before transferring to a wire rack to cool.