Place chicken in 3 1/2- to 4-quart slow cooker. Top with onion, bay leaf, pepper and gravy. Place celery on gravy.
Cover and cook on Low heat setting 8 to 10 hours.
2
About 30 minutes before serving, make and bake 8 biscuits using Bisquick mix and milk as directed on package.
3
Meanwhile, gently stir frozen vegetables into chicken mixture. Increase heat setting to High. Cover and cook 15 minutes. Remove bay leaf.
4
For each serving, split biscuit and place in soup bowl or tart pan. Spoon about 3/4 cup chicken mixture on top of biscuit.