Cut the head of cauliflower into bite-sized florets. Place the cauliflower florets into a large bowl and toss with olive oil and your preferred seasoning.
Place coated florets in the air fryer basket. For the crispiest texture, make sure to fry them in a single layer; you might have to do two batches depending on the size of your air fryer. Cook at 390°F for 14-15 minutes, checking and stirring after 10 minutes.
If using parmesan, at the 12 minute mark, sprinkle shredded parmesan over the florets and then place basket back in the air fryer for two more minutes.