In a bowl, combine the Parmesan, breadcrumbs, garlic granules, smoked paprika and mustard powder. Mix and season to taste with salt and pepper. Add the eggs to another bowl.
Dip a cauliflower floret into the egg allowing any excess to drip off. Then dip into the breadcrumb mixture, coating on all sides. Place into the air fryer basket and repeat with the remaining cauliflower.
Spray with low-calorie cooking spray and air-fry at 180°C for 10 minutes. Flip the cauliflower over and cook for a further 10 minutes. The breadcrumbs should be crispy and cauliflower cooked through. You may need to cook in batches depending on the size of your air fryer.
When you've turned the cauliflower over, make the cheese dipping sauce. Add the flour to a microwavable bowl or jug and pour in the milk, mix with a balloon whisk until smooth. Pop into the microwave in 1 minute bursts until the milk and flour have thickened. Ours took about 2 minutes but this will depend on the wattage of your microwave.
Add the cheese, mustard powder and Sriracha and mix, until the cheese has melted and the sauce is smooth. Season to taste with salt and pepper.
Remove the cauliflower from the air fryer and serve alongside the dipping sauce.