Preheat the oven to 400°F.
Wash the sweet potatoes and pierce them several times with a fork. Place them on a baking sheet and bake for 45-60 minutes, or until tender.
While the sweet potatoes are baking, heat olive oil in a large skillet over medium heat. Add diced onion and bell pepper, cooking until softened, about 5-7 minutes.
Stir in minced garlic and cook for an additional minute.
Add black beans, diced tomatoes (with juice), corn, chili powder, cumin, smoked paprika, cayenne pepper, salt, and pepper to the skillet. Stir well and let simmer for about 10 minutes.
Once the sweet potatoes are done, remove them from the oven and let cool slightly. Cut each sweet potato in half lengthwise and scoop out a bit of the flesh to create a boat shape.
Fill each sweet potato half with the chili mixture, pressing down gently to pack it in. Top with shredded cheese and return to the oven for an additional 10-15 minutes, or until the cheese is melted and bubbly.
Remove from the oven and let cool for a few minutes. Garnish with fresh cilantro and serve with a dollop of sour cream or Greek yogurt, if desired.