Break head of cauliflower into same-sized florets. In a large bowl, stir hot sauce, butter, salt, and garlic powder. Add cauliflower; toss to combine. Add cornstarch; toss to coat.
Using tongs and working in batches if necessary to avoid overcrowding, place cauliflower in an air-fryer basket. Cook at 350°, tossing halfway through, until browned in spots, about 15 minutes.
In a small bowl, stir blue cheese, sour cream, buttermilk, and mayonnaise; season with salt and pepper.
Serve cauliflower with blue cheese dressing alongside.
