Preheat the oven to 400°F (200°C).
Wash the sweet potatoes thoroughly and pierce them several times with a fork. Place them on a baking sheet and bake for about 45-60 minutes, or until tender.
While the sweet potatoes are baking, mix the shredded chicken with BBQ sauce in a bowl. Set aside.
Once the sweet potatoes are done, remove them from the oven and let them cool slightly.
Cut each sweet potato in half lengthwise and scoop out a portion of the flesh, leaving a small border around the edges.
In a mixing bowl, combine the scooped sweet potato flesh, sour cream, garlic powder, onion powder, salt, and pepper. Mix until smooth.
Fold in the BBQ chicken mixture and half of the shredded cheddar cheese.
Spoon the mixture back into the sweet potato skins, dividing it evenly.
Top each filled sweet potato with the remaining cheddar cheese.
Return the stuffed sweet potatoes to the oven and bake for an additional 15-20 minutes, or until the cheese is melted and bubbly.
Remove from the oven and garnish with sliced green onions before serving.