Place chicken pieces in the insert of a slow cooker. Sprinkle with Italian salad dressing mix. Add in the carrots and celery. Pour/spread the condensed soup over top. Cover and cook on HIGH for 4 hours (or LOW for 7-8).

Remove chicken from slow cooker and set aside to cool slightly. When cool enough to comfortably handle, remove chicken from the bone and shred. 

In a small bowl, combine the biscuit mix, cheese, baking soda, biscuit seasoning packet, and water. 

Return the chicken to the slow cooker. Whisk in the gravy mix and milk and change heat to HIGH. 

Drop spoonfuls of biscuit dough on top of the chicken mixture. Recover and cook on HIGH for 1 hour. Alternatively, you can heat your oven for 350 F and bake the mixture for 15 minutes until dumplings are baked through (I assume no responsibility for anything happening to your insert, but mine was fine).