Whisk dry ingredients:

Combine flour, cocoa powder, sugar, baking powder, baking soda, and salt in a bowl using a whisk.

Mix wet ingredients:

In a separate bowl, mix together milk, oil, eggs, and vanilla extract.

Combine wet and dry:

Add the wet mixture to the dry mixture and stir only until incorporated.

Fold in chocolate chips:

Gently fold in the chocolate chips.

Preheat air fryer:

Heat the air fryer to 320°F (160°C).

Fill muffin cups:

Divide the batter among 12 muffin cups.

Air fry muffins:

Cook in the air fryer for 12-15 minutes. Test doneness by inserting a toothpick into the center; it should come out clean.

Cool and serve:

Allow muffins to rest in the pan for a few minutes, then move them to a wire rack to cool fully before serving.