Preheat the oven to 400°F.
Peel (if desired) and dice the sweet potato into 1-inch cubes. Toss with a drizzle of olive oil (optional), garlic powder, salt, and pepper, and spread on a baking sheet.
Roast the sweet potato cubes in the oven for 20-25 minutes, until tender and slightly caramelized.
While the sweet potatoes roast, season the chicken breast lightly with salt, pepper, and a pinch of garlic powder. Grill or pan-cook the chicken on medium heat until fully cooked (internal temperature reaches 165°F), about 6-8 minutes per side.
Once cooked, cut the chicken into bite-sized pieces and toss with buffalo sauce.
In a small bowl, mix nonfat Greek yogurt with a little extra buffalo sauce if preferred, to create a creamy drizzle.
Slice the celery into thin sticks for a refreshing crunch.
Plate the buffalo chicken alongside the roasted sweet potato cubes, drizzle with the creamy Greek yogurt buffalo sauce, and garnish with the crunchy celery sticks.