Preheat the air fryer to 360F / 180c.
Remove the outer leaves from the cauliflower, and trim the bottom of the stem if needed.
Melt the butter, and mix in the seasonings.
Brush the head of cauliflower with most of the butter mixture (it's less messy to do this in the air fryer basket) so that the cauliflower is well coated.
Set the cauliflower to roast in the air fryer at 360F / 180c for 40 minutes.
Halfway through cooking, brush the rest of the seasoned butter over the cauliflower, this will help it to stop frying out.
The cauliflower should be tender, with a little bite, once cooked.