Place the frozen chicken breasts in the Crock-Pot and sprinkle evenly with the salt, poultry seasoning, and black pepper. Dot the chicken with the thinly sliced butter.
Cover the Crock-Pot and set to cook on LOW heat for 6-8 hours. For a quicker option, cook on HIGH heat for 4-6 hours.
Ensure the chicken has reached a safe internal temperature of at least 165°F by using a meat thermometer.
Once cooked, shred the chicken with two forks and use it as needed in your favorite recipes.
To save for future meals, let the chicken cool, then transfer to a freezer-safe zippered bag and freeze for up to one month.