Prep the air fryer: Preheat your air fryer to 320°F (160°C) for 3–5 minutes. Line the basket with a piece of parchment cut to fit, and poke a few holes to keep airflow.

Cream the butter and sugars: In a medium bowl, beat the butter, granulated sugar, and brown sugar until light and fluffy, about 1–2 minutes. A hand mixer is easiest, but a whisk works too.

Add egg and vanilla: Mix in the egg and vanilla until fully combined. Scrape the bowl so everything blends evenly.

Whisk the dry ingredients: In a separate bowl, whisk the flour, baking soda, baking powder, and salt.

Combine the dough: Add the dry ingredients to the wet and mix just until no streaks of flour remain. Do not overmix.

Fold in mix-ins: Stir in 1–1 1/4 cups of your chosen add-ins. Keep larger chunks small so they cook evenly.

Chill briefly (optional but helpful): For thicker cookies, chill the dough 15–20 minutes. It helps prevent spreading.

Portion the dough: Scoop into 1 1/2-tablespoon balls (about golf ball size). Arrange 4–6 cookies in the air fryer, spaced apart. Gently flatten the tops to about 1/2-inch thick.

Air fry: Cook at 320°F (160°C) for 6–9 minutes. Start checking at 6 minutes. The edges should look set and lightly golden; centers may look a touch soft.

Rest and repeat: Let cookies cool in the basket 3–4 minutes to firm up, then transfer to a rack. Repeat with remaining dough.

Adjust as needed: If cookies spread too much, chill dough longer or lower temp slightly. If they’re too pale, add 1–2 minutes next batch.