This slow cooker chicken dish pairs tender bone-in pieces with sweet apples and savory onions. Fresh rosemary adds a fragrant, earthy note that balances the rich cream of celery soup and chicken broth base. It is a hands-off meal that fills the kitchen with warm, comforting aromas as it simmers throughout the day. Serve the rich, creamy sauce and tender chicken over a bed of warm rice for a satisfying autumn dinner.