Preheat the oven to 450 degrees F. Line a rimmed broiler-safe baking sheet with foil for easy cleanup.
Make the blue cheese dressing by mixing all its ingredients in a small bowl. Cover and refrigerate until ready to use.
Make the buffalo sauce: In a large microwave safe bowl, melt the butter. Whisk in the hot sauce and garlic powder. Set aside.
In another large bowl, toss the cauliflower florets with the olive oil, salt and garlic powder. Spread on the baking sheet and roast until tender-crisp, about 15 minutes.
Switch the oven to broil and set an oven rack 6 inches below the heat element (not directly below).
Whisk the hot sauce mixture again. Add the roasted cauliflower florets and toss to coat. Return the cauliflower florets to the baking sheet and broil until browned and bubbly, keeping a close eye on them so they don't burn, 2-3 minutes.
Serve the buffalo cauliflower hot, with the blue cheese dressing and celery sticks.
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Notes
When making this recipe, it's best to use large cauliflower florets and to roast them for a short time at a high temperature.This helps the cauliflower retain some crispiness. Otherwise, it can turn mushy. Still delicious, but mushy.You roast the cauliflower in two stages. First without the sauce, then coated with the buffalo sauce.For the second phase, I actually prefer to use the broiler. It browns the cauliflower better than baking does and it helps prevent sogginess.