Preheat the oven to 200C/400F (fan).
Start by making the bang bang sauce. Place the mayonnaise, sweet chilli sauce, sriracha, and honey in a small bowl and mix together, then put to one side while you make the crispy cauliflower.
Place the buttermilk, egg, garlic salt, white pepper and salt in a bowl and lightly whisk to combine.
Place the panko, paprika, remaining salt, pepper, garlic salt, celery salt, white pepper, and olive oil in a second bowl and mix together until the olive oil is combined with the breadcrumbs evenly.
Dip the cauliflower pieces in the buttermilk mixture to coat, then dredge in the panko mixture.
Place the coated cauliflower on a baking tray.
Place the baking tray in the oven and cook for 20-25 minutes, until the cauliflower is tender and the coating is golden.
Transfer the cooked crispy cauliflower to a serving bowl and drizzle over half the sauce.
Sprinkle over the spring onions and sliced chilli, then serve with the remaining bang bang sauce for dipping.