Prepare the cauliflower by washing it thoroughly, then pat dry with paper towels. Cut into evenly-sized florets about 1½ inches in size – consistent sizing ensures they cook at the same rate.
Place the florets in a large mixing bowl and drizzle with olive oil. Toss well to ensure each piece is lightly coated.
Add all the dry seasonings (garlic powder, paprika, onion powder, dried herbs, cayenne if using, salt, and pepper) to the bowl. Mix thoroughly until the cauliflower is evenly coated with the spice mixture.
Preheat your air fryer to 380°F (190°C) for 3 minutes. This step is crucial for achieving the best crispy texture.
Arrange the seasoned cauliflower in the air fryer basket in a single layer with some space between pieces. Work in batches if necessary – overcrowding will result in steaming rather than crisping.
Cook for 12-15 minutes, pausing halfway through to shake the basket or turn the florets with tongs. Look for golden brown edges and test a piece for desired tenderness.
If using Parmesan cheese, sprinkle it over the cauliflower during the last 2 minutes of cooking for a crispy, savory finish.
Transfer the finished cauliflower to a serving dish, squeeze fresh lemon juice over the top if desired, and garnish with chopped fresh parsley.