How to Make It
Cook bacon in a large skillet over medium-high until crisp. Remove bacon from pan, reserving 1 teaspoon drippings in pan. Set bacon aside.
Sprinkle chicken with seasoning blend. Add chicken to bacon drippings in pan; cook 8 minutes, browning on all sides. Transfer chicken using a slotted spoon to a 6-quart electric slow cooker, reserving any drippings in pan. Add leek, carrot, and celery to drippings in pan; sauté 5 minutes. Stir in 1 cup stock, scraping pan to loosen browned bits. Add leek mixture, bacon, remaining 3 cups stock, salt, pepper, and thyme sprigs to slow cooker. Cover and cook on LOW for 2 hours. Add potatoes; cover and cook on LOW for 2 more hours or until potatoes are tender.
Remove chicken from slow cooker with a slotted spoon; discard thyme sprigs. Cut chicken into bite-size pieces; discard bones. Return chicken to slow cooker; add spinach, stirring until spinach wilts.