In a small bowl, combine the all-purpose flour, baking soda, and salt; set aside.

In a large mixing bowl, cream together the softened butter, brown sugar, and granulated sugar using a hand mixer or a whisk until the mixture is light and fluffy (about 2-3 minutes).

Add the egg and vanilla extract to the butter mixture, beating until smooth and well combined.

Gradually mix in the dry ingredients until just incorporated—do not overmix.

Fold in the chocolate chips and walnuts (if using) until evenly distributed throughout the dough.

Preheat your air fryer to 320°F (160°C) for about 5 minutes.

Line the air fryer basket with parchment paper. Using a cookie scoop or tablespoon, drop spoonfuls of dough onto the parchment, spacing them about 2 inches apart.

Air fry the cookies in batches (about 4-6 at a time) for 8-10 minutes, until edges are lightly golden but the centers are still gooey.

Let the cookies cool in the basket for 5 minutes before transferring them to a wire rack to cool completely.