Preheat your air fryer to 325°F (165°C).

In a mixing bowl, beat the softened butter with brown sugar and granulated sugar using an electric mixer for about 1 minute, until smooth and creamy.

Add the egg yolk and vanilla extract, then mix until fully incorporated.

In a separate bowl, whisk together the flour, baking soda, cornstarch, and salt.

Slowly add the dry ingredients to the wet mixture, mixing on low speed until a soft dough forms.

Gently fold in the chocolate chips using a spatula or spoon.

Line the air fryer basket with parchment paper. Scoop about 2 tablespoons of dough per cookie, roll into balls, and place them in the basket, leaving space between each.

Cook in batches at 325°F (165°C) for 5–7 minutes, or until the edges turn lightly golden.

Let the cookies sit in the air fryer for 2–3 minutes before transferring them to a cooling rack.