Set oven to broil.
Place chicken in a medium bowl and mix in taco seasoning packet and breadcrumbs using either your fingers or a spoon.
Form meatballs, around 2 inches in diameter and place on a greased baking sheet.
Broil meatballs until browned, about 5 minutes, turning meatballs half-way through.
Transfer meatballs to the slow cooker and cover with enchilada sauce. Cook on low for at least 2 hours.
Serve with cheese and cilantro. Use sour cream as a dipping sauce (optional).