Combine cumin, coriander, and cinnamon in a small bowl; sprinkle over onion in pan. Cook 1 minute.
Add chiles and garlic to pan; cook 2 minutes or until chiles soften.
Add broth and next 4 ingredients (through rind) to pan; bring to a boil.
Add chicken to pan; cover, reduce heat, and simmer 10 minutes or until chicken is done.
Remove chicken from pan; shred with 2 forks. Set aside.
Add chocolate to chile mixture; let stand until chocolate melts. Using an immersion blender in pan, puree the chocolate mixture until smooth. Cook over medium heat 20 minutes or until reduced to 3 1/2 cups.
Add shredded chicken to sauce; stir in salt and pepper.