In a Dutch oven or extra large skillet, cook turkey over medium heat until no longer pink. Create a circle in center and pour olive oil into pan. Add onion, bell pepper, jalapenos (if using), garlic and sweet potatoes. Cook for 5 minutes, stirring often.
Add contents to a 6.5-quart slow cooker, along with tomatoes, black beans, chili powder, cumin, paprika, cayenne pepper and chicken broth. Mix well. Cover and cook on Low heat for 7-8 hours or High heat for 5-6 hours.
Serve hot. Top with avocados, sour cream and shredded cheese, if desired.