Preheat your oven to 425°F (220°C) and line a baking sheet with parchment paper.
In a large bowl, whisk together the flour, garlic powder, onion powder, smoked paprika, salt, and black pepper.
Add the milk and mix until a smooth batter forms.
Dip each cauliflower floret into the batter, ensuring it is well coated, and shake off any excess.
Arrange the coated cauliflower on the prepared baking sheet in a single layer.
Lightly spray with cooking spray and bake for 20-25 minutes, flipping halfway through, until golden and crispy.
In a separate bowl, mix the buffalo sauce with melted butter.
Remove the cauliflower from the oven and toss it in the buffalo sauce mixture until well coated.
Return to the oven for an additional 5 minutes to set the sauce.
Serve immediately with ranch or blue cheese dressing and celery sticks.