Preheat oven to 450°F (230°C) and line a baking sheet with parchment paper.
In a large mixing bowl, whisk together flour, water, garlic powder, salt, and black pepper until smooth.
Add cauliflower florets to the batter and toss until fully coated.
Place florets on the prepared baking sheet in a single layer with space between each piece.
Bake for 20 minutes, flipping the florets halfway through the cooking time.
In a separate bowl, combine the buffalo hot sauce and melted butter.
Remove cauliflower from the oven and coat each piece thoroughly with the buffalo sauce mixture.
Return to the oven and bake for another 10 minutes until the coating is crispy and the sauce is bubbly.
Serve immediately with celery sticks and ranch or blue cheese dressing.