In a small mixing bowl, cream together the softened butter, brown sugar, and granulated sugar until smooth.
Add the salt, egg, and vanilla extract. Stir until the mixture is glossy and combined.
Add the flour and baking powder. Mix gently, just until no dry streaks remain — do not overmix.
Fold in the chocolate chips.
Spray two 10-ounce oven-safe ramekins with non-stick cooking spray.
Divide the dough evenly between the ramekins, filling each about two-thirds full. Press a few extra chocolate chips on top.
Place the ramekins in the air fryer basket. Air fry at 320°F (160°C) for 7 minutes. Start checking at 6 minutes — the edges should be set and lightly golden, and the center should look slightly soft.
Remove carefully (the ramekins will be very hot) and let cool for 2–3 minutes before eating. Top with vanilla ice cream if desired.