Preheat your oven to 400°F (200°C) and line a baking sheet with foil or parchment paper for easier cleanup.
Pierce each sweet potato several times with a fork to allow steam to escape during baking. Place them directly on the oven rack with the lined baking sheet below to catch any drips.
Bake for 45-50 minutes until the sweet potatoes are completely tender when pierced with a fork. Larger potatoes may need up to 60 minutes.
While the potatoes bake, prepare the buffalo chicken. In a medium bowl, combine the shredded chicken with the melted butter and buffalo sauce, stirring until the chicken is evenly coated. Set aside.
Once the sweet potatoes are done, remove from oven and let cool slightly, about 5 minutes, until they’re comfortable to handle.
Cut a slit lengthwise down the center of each sweet potato, being careful not to cut all the way through. Gently push the ends toward the center to open the potato up.
Fluff the inside of each potato with a fork, then season with a pinch of salt and pepper to taste.
Divide the buffalo chicken mixture evenly among the four sweet potatoes, stuffing it into the openings.
Top each potato with blue cheese crumbles and return to the oven for 5 minutes to warm through and slightly melt the cheese.
Remove from the oven and drizzle with ranch dressing, sprinkle with green onions, cilantro, and celery (if using), and add an extra drizzle of buffalo sauce if desired.