Preheat air fryer at 400 F degrees. To a large bowl, add cauliflower and drizzle with oil and lemon juice, toss to coat evenly. Sprinkle with garlic powder, smoked paprika, salt and pepper; toss to coat.
Transfer cauliflower into the basket of air fryer leveling into a single layer. Air fry for 14 minutes at 400 degrees F, shaking once or twice.
At 12 minute mark, sprinkle with Parmesan cheese and keep cooking.
Store: Refrigerate in an airtight container for up to 4 days.
Make ahead: Refrigerate seasoned cauliflower in an airtight container for up to 24 hours and then cook as per recipe.
Reheat: Reheat air fryer cauliflower in air fryer at 300 degrees F for 3-4 minutes or until warm.
For crispy results, you need the oil, so don't try and skip it!
Work in batches. You want an even single layer spread out in the basket, but also leaving enough room for the air to circulate and the heat to evenly distribute throughout. If not, you'll end up with soggy cauliflower.