Prep the cauliflower. Rinse, dry, and cut the cauliflower into evenly sized florets.
Aim for 1- to 1.5-inch pieces so they cook at the same rate.
Preheat the air fryer. Set it to 390°F (200°C) for at least 3 minutes. A hot basket helps the coating crisp up right away.
Set up three bowls. In one bowl, add flour. In the second, whisk the egg with 1 tablespoon of water.
In the third, mix panko, Parmesan, garlic powder, onion powder, smoked paprika, salt, pepper, and cayenne.
Toss with oil. Drizzle the cauliflower with olive oil and toss to coat lightly. This helps the seasonings stick and promotes browning.
Coat the florets. Work in batches: dredge each floret in flour, dip in egg, then press into the panko mixture until well coated. Shake off excess.
Load the basket. Spray the air fryer basket with nonstick spray.
Arrange florets in a single layer with a little space between them. Don’t overcrowd; cook in batches if needed.
Air fry. Cook for 10–13 minutes, shaking the basket or flipping the florets halfway through. They’re done when the coating is deep golden and the stems are tender when pierced.
Season and serve. Sprinkle with a pinch of salt while hot.
Serve right away with your favorite dipping sauce.