Combine all spice mix ingredients in a small bowl. Stir well to combine. Set aside.
Combine olive oil, onion, celery and garlic in a medium large microwave-safe bowl. Stir well to combine, then add the spice mix and stir again.
Cover bowl with plastic wrap and place in microwave. Cook on high power for 2 minutes. Remove from microwave, stir well, then cook another 2 minutes. Add to the slow cooker.
Drain and rinse 2 cans of the beans. Combine beans with chicken broth in a blender container. Blend on high for about 30 seconds or until smooth. Add to the onion mixture in the slow cooker.
Drain and rinse remaining 4 cans of beans, Add beans, tomatoes, green chilis and chicken to slow cooker and stir to combine. Cover and cook on low for 6-8 hours.
If using Neufchâtel cheese, stir in during the last 30 minutes of the cooking time, stirring occasionally.
Serve top with cheddar or Monterrey Jack cheese, chopped cilantro and tortilla chips, if desired.