In a mixing bowl, combine the melted butter and brown sugar, stirring until well combined.
Add the egg yolk and vanilla extract to the butter-sugar mixture. Mix until everything is fully integrated.
In another bowl, whisk together the all-purpose flour and baking soda. Gradually add this dry mixture to the wet ingredients, stirring until just combined.
Gently fold in the semisweet chocolate chunks or chips until evenly distributed throughout the cookie dough.
Preheat your air fryer to 320°F (160°C) for about 3 minutes.
Using a cookie scoop or a tablespoon, portion out the dough and shape it into balls. Place them on a piece of parchment paper, leaving space for them to spread while cooking.
Carefully place the cookie dough balls into the air fryer basket, ensuring they are spaced apart. Air fry for 8-10 minutes or until the edges are golden and the centers look slightly underbaked.
Remove the cookies from the air fryer and let them cool on a wire rack.
