Preheat oven.  I used convection bake at 400.  For conventional ovens, increase the temp by 25, or increase your bake time.

Blend butter and both sugars in stand mixer until well incorporated and lightened, approximately 3 minutes.  Add eggs and vanilla.  Mix dry ingredients (flour, cornstarch, baking powder, baking soda, and salt) separately, and then add to the butter mixture.  Stir in chocolate chips.  Using a large ice cream scoop, portion out cookies onto parchment lined cookie sheets.  Bake on middle rack of preheated oven for about 8 minutes until set and golden brown on the edges.  Remove from oven and let cool on cookie sheet for 5-10 minutes before transferring to a rack to cool completely.