Combine the flour, cornstarch, garlic powder, paprika, onion powder, and salt in a large bowl and whisk to combine.
Pour the water into the bowl and whisk until a smooth batter forms.
Place the cauliflower florets in the batter and gently toss until all the florets are evenly coated.
Remove the florets one by one, letting excess batter drip off, and place them in a single layer on the baking sheet. Work in batches if necessary to avoid overcrowding the pan.
Bake for about 20 minutes, flipping halfway, until browned and crispy.
Meanwhile, make the Buffalo sauce. Place the hot sauce, melted butter, and maple syrup in a bowl and stir to combine.
Remove the florets from the oven and place them in a large mixing bowl. Gradually add the Buffalo sauce and gently toss until the florets are evenly coated.
Return the florets to the baking sheet and bake for an additional 15-20 minutes, flipping halfway, until browned and crispy again.