Preheat oven to 375 degrees.
Add cold butter to the bowl of a stand mixer. Beat on medium-low with paddle attachment for 1 minute.
Add sugar and brown sugar. Beat on low for 1 minute. Beat on medium-high for 1 minute. Scrape down the bowl.
Add eggs and vanilla. Mix until mostly combined.
Add flour, cornstarch, baking soda, baking powder, and salt. Mix for just a few seconds on low.
Add chocolate chips. Mix until cookie dough is completely mixed and comes together.
Roll dough into 0.4 oz cookies. I like to use a 0.75 oz (#40) cookie scoop and divide the dough ball in half, then roll each half into a ball. (It’s roughly 2 ½ teaspoons a dough ball).
Place dough balls on a cookie sheet. Bake one sheet at a time on the middle rack for 5-7 minutes. Cookies should be slightly firm but still soft. Let them cool on the cookie sheet until set up enough to transfer.
Store in an airtight container.
