Pat the chicken drumsticks dry with paper towels and arrange them in a single layer in your slow cooker.

In a medium bowl, whisk together the barbecue sauce, apple cider vinegar, brown sugar, Worcestershire sauce, garlic powder, onion powder, smoked paprika, and black pepper until well combined.

Pour the sauce mixture over the chicken drumsticks, making sure each piece is well coated. Add the chicken broth or water to the bottom of the slow cooker to prevent sticking and create steam.

Cover and cook on LOW for 6-7 hours or HIGH for 3-4 hours. The chicken is done when it reaches an internal temperature of 165°F and the meat easily pulls away from the bone.

For a thicker sauce, carefully transfer the cooked drumsticks to a serving platter. Mix 2 tablespoons of cornstarch with 2 tablespoons of cold water, then stir this slurry into the sauce in the slow cooker. Cook on HIGH for 15-20 minutes until thickened.

Return the drumsticks to the slow cooker, coat with the thickened sauce, and serve immediately. For extra caramelization, you can broil the sauced drumsticks for 2-3 minutes before serving.