Preheat the oven to 450 degrees F. Line a parchment paper over the baking sheet and keep it aside.
Cut the cauliflower into florets, wash them, and dry them with a kitchen towel. Keep it aside.
In a medium bowl, combine flour, paprika, garlic powder, salt, black pepper, and buttermilk. Mix the batter until smooth without any lumps.
Add the cauliflower florets and coat them well with the batter.
Place the panko breadcrumbs in a wide bowl, and dredge the batter-coated cauliflower florets into the panko breadcrumbs. Press them to coat evenly.
Arrange the cauliflower florets on the prepared baking sheet. Bake it for 25-30 minutes until they turn golden and crispy. Transfer the cauliflowers to a large bowl. Set it aside.
Meanwhile, prepare the sauce. In a medium bowl, combine mayonnaise, sweet chili sauce, sriracha, ketchup, honey, vinegar, and black pepper. Mix until smooth and creamy.
Pour the prepared sauce over the cauliflower and toss it well until evenly coated.
Garnish the crispy bang bag cauliflower with chives and red chili flakes and serve.