First, preheat the oven to 400F. Then line baking sheets with parchment paper. Using a bowl combine all dry ingredients flour, baking powder, baking soda, cornstarch and salt. Mix well. In a different bowl combine butter, brown sugar and sugar, whisk with a mixer until smooth, about 2 minutes.

Next, add 1 egg and whisk, add another egg and whisk again. Whisk in vanilla extract.

After, add flour and beat on low speed, until all ingredients are combined. Using spatula fold in walnuts and chocolate chips.

Using large ice cream scoops add 1 scoop of cookie dough onto your hand and shape 12 giant cookies. Place cookies onto a baking sheets 2 inches apart (12 cookies per large baking sheet or 6 cookies on a small baking sheet).

Bake on center rack for 12 minutes or until slightly golden color (don't over bake them). After cool on a baking sheet. Enjoy while warm.