Preheat the air fryer to 325° if required by your model.
In a large bowl, beat together the butter, brown sugar, and sugar until light and fluffy. Add the egg and vanilla extract and beat to combine.
In a separate bowl, whisk together the flour, cornstarch, baking soda, and salt. Add to the butter mixture and beat to combine.
Fold in the chocolate chips.
Use a tablespoon/cookie scoop to scoop a heaping spoonful of dough and roll the dough into a ball. Slightly press the ball down and place it in a lined air fryer basket, leaving at least one inch of space between each cookie in the basket.
Place the basket in the air fryer and cook for 5 to 7 minutes, until the outside is brown and the inside is still slightly soft.
Place the basket on a wire cooling rack to cool until the basket is safe to touch, then transfer the cookies on the parchment paper lining to a wire cooling rack to cool completely. Continue cooking in batches until all the dough has been used.