In a small bowl, combine arrowroot starch, egg, milk, garlic powder, onion powder, and salt to make a batter. Heat a large skillet with 1/4 cup of olive oil on medium-high heat. When hot, dip cauliflower florets in the batter and add to hot oil. Pan fry each side for 2 minutes, in the meantime, preheat air fryer if needed at 370. Place cauliflower in the air fryer. Air fry for 10-12 minutes. Repeat by pan-frying rest of cauliflower, place on a cooling rack in the meantime till air fryer is available.