Preheat the oven to 375 degrees F.
Remove the stem and outer leaves from 1 large cauliflower, keeping the head intact. Pat the cauliflower dry.
In a small bowl, stir together 1 teaspoon garlic powder, ½ teaspoon smoked paprika, ½ teaspoon salt, and ½ teaspoon pepper.
Place the cauliflower in a large oven-safe skillet or baking dish. Drizzle 2 tablespoons olive oil over the cauliflower and rub it all over so the surface is evenly coated.
Sprinkle the spice mixture evenly over the cauliflower, turning the head so all sides are seasoned.
Cover the skillet tightly with aluminum foil (or use a lid) and roast in the preheated oven for 30 minutes.
Remove the foil and continue roasting uncovered for 1 hour more, or until a knife or skewer inserted into the center of the cauliflower meets little resistance and the head is tender.
Remove the cauliflower from the oven and drizzle buffalo wing sauce over the top to taste.
Evenly sprinkle ⅓ cup crumbled blue cheese over the cauliflower, then scatter ⅓ cup fresh cilantro, 2 tablespoons chopped chives, and 2 green onions (thinly sliced) on top.
Slice the cauliflower into wedges or slices and serve immediately.