Use a 4 to 5 quart slow cooker. Rinse the lentils under cold water until it runs clear. Dump into the slow cooker. Add broth and water. Add diced onion and celery. Add all spices, the garlic, and chilies. Stir to combine. Lay chicken breast halves on top of the assembled food. Cover and cook on low for about 7 hours, or on high for about 4. Before serving, remove chicken from the slow cooker, chop it up, and stir back in. Serve over basmati rice if desired.