Heat a skillet over medium heat and cook the ground turkey, breaking it up with a spoon until it is no longer pink. Add the diced onion and minced garlic and cook for another 2-3 minutes until the onion softens.
Transfer the turkey mixture to the slow cooker. Add the pumpkin puree, black beans, diced tomatoes, and chicken broth.
Stir in the chili powder, cumin, salt, and black pepper until everything is evenly combined.
Cover and cook on low for 6-7 hours or on high for 3-4 hours.
Taste and adjust salt if needed. Ladle into bowls and top each serving with a dollop of Greek yogurt and a sprinkle of chopped cilantro.