Season the ground beef with half the salt and pepper, then roll it into mini meatballs (about 1 tablespoon each). No need to brown them—they’ll cook right in the soup!
Cut the cabbage into small strips.
Layer in the slow cooker: Add the chicken breasts, meatballs, cabbage, diced tomatoes, spices, and chicken stock.
Let it cook on low for 7–8 hours or high for 4–5 hours, until everything is tender and flavorful.
Shred the chicken right in the pot (two forks or a hand mixer works great!), then ladle the soup into bowls and let everyone top theirs however they like!