Preheat the air fryer to 320°F for 3 to 5 minutes.
In a large bowl, whisk the flour, sugar, cocoa powder, baking powder, and baking soda.
In a second bowl, whisk the milk, eggs, vanilla, and melted butter until smooth.
Pour the wet ingredients into the dry and stir just until combined. Fold in the chocolate chips.
Lightly grease silicone muffin cups and fill each about two-thirds full.
Place the cups in the basket in a single layer. Air fry for 10 to 12 minutes, until a toothpick in the center comes out clean or with a few moist crumbs.
Cool in the cups for 5 minutes, then remove. Repeat with the remaining batter.