Add the chicken breasts to the bottom of the slow cooker. Season with 1/4 teaspoon pepper.
Whisk together the gravy packets, cream of mushroom soup, 1/4 teaspoon pepper, garlic, dried thyme, and water in a bowl. Pour over chicken.
Cover and cook on low for 4-6 hours.
Once the chicken is cooked, shred and serve with or over mashed potatoes, rice, stuffing, or noodles.
To thicken gravy, if needed: In a small bowl, whisk 2 tablespoons of cold water and 2 tablespoons of cornstarch together. Once the cooking time is up and your chicken is cooked and shredded, add this mixture to the slow cooker. Cover and let cook for 1 - 15 minutes or until thickened.