Place the chicken breasts in a single layer in the slow cooker.
Sprinkle the Italian dressing mix evenly over the chicken.
Pour the bottled Italian dressing over the chicken.
Dollop the cream of chicken soup over the top if using. Season lightly with salt and pepper.
Cover and cook on LOW for 6–7 hours or HIGH for 3–4 hours until the chicken reaches 165°F and is tender.
Serve warm with sauce spooned over rice, noodles, or mashed potatoes.
Notes
For extra creaminess, include the cream of chicken soup. For a lighter version, omit the soup and enjoy a tangier sauce. Always cook chicken to an internal temperature of 165°F.