Using mixer, beat butter in your mixing bowl until it turns a pale yellow about 2-3 minutes.
Beat in sugars until the mixture is fluffy.
Mix in egg, followed by vanilla until well combined.
Add flour, cornstarch, baking powder, baking soda, cinnamon and salt to wet mixture and mix together to form your dough.
Using a large cookie scoop (1/4 cup scoop), scoop cookies and then roll in cinnamon sugar mixture. Very lightly pat down cookie dough or not at all, depending on thickness you want cookies. Cookies will spread out, so be sure to keep the unbaked cookie dough thick on the baking sheet.
Bake cookies for 10-12 minutes to partially under-bake the dough, to get the crispy, golden brown edges on the outside and the soft and chewy inside.