Step 1: Season the Chicken - Start with the chicken breasts and sprinkle them evenly with the kosher salt, black pepper, and garlic powder. I like seasoning the chicken before it goes into the slow cooker instead of relying entirely on the sauce because it gives the meat itself a little more character. You do not need to let it sit or marinate. Just make sure both sides get a light, even coating.
Step 2: Arrange the Chicken in the Slow Cooker - Place the seasoned chicken breasts in the bottom of a 6 quart slow cooker. Try to arrange them in a fairly even layer rather than stacking them into one thick pile. A little overlap is completely fine. The goal is simply to give the hot sauce plenty of contact with the chicken as it cooks.
Step 3: Whisk the Creamy Sauce - In a medium bowl, combine the cream of chicken soup, cream of celery soup, onion soup mix, chicken broth, poultry seasoning, and dried thyme. Whisk until everything is smooth and evenly blended. The mixture will look fairly loose at this stage, but it thickens while the chicken cooks and eventually becomes the creamy sauce that coats the rice.
Step 4: Cover the Chicken With the Sauce - Pour the soup mixture evenly over the chicken breasts. I usually use a spoon to gently spread it around so every piece of chicken is covered. There is no need to stir anything underneath the chicken. The slow cooker will create plenty of moisture as it heats, and all those savory ingredients will mingle together on their own.
Step 5: Add the Butter - Arrange the sliced butter across the surface of the sauce. Spreading the slices around instead of dropping the entire stick into one spot helps the butter melt evenly into the creamy mixture. As it melts, it works its way through the sauce and gives the chicken that rich flavor the recipe is known for.
Step 6: Slow Cook Until Tender - Cover the slow cooker and cook on LOW for 5 to 6 hours or on HIGH for 3 to 4 hours. I prefer LOW when the schedule allows because chicken breasts tend to stay especially tender with the gentler heat. The chicken is ready when it is fully cooked and easily pulls apart with a fork. For food safety, the center should reach 165°F.
Step 7: Shred the Chicken - Carefully lift the chicken breasts out of the slow cooker and transfer them to a cutting board or shallow bowl. Shred them with two forks or chop them into small bite sized pieces. I usually shred mine because all those little strands grab onto the sauce beautifully, which means you get creamy chicken in nearly every spoonful.
Step 8: Stir the Chicken Back Into the Sauce - Return the shredded chicken to the slow cooker and stir it gently into the buttery sauce. Give it a minute to settle back into all that creamy goodness. At this point, the mixture should be thick, fragrant, and looking very much like dinner.
Step 9: Fold in the Cooked Rice - Add the cooked long grain white rice and fold it gently into the chicken mixture until the rice is evenly coated. You are not trying to cook the rice here. You are simply warming it through and letting it absorb some of the sauce. Stir gently so the grains do not break down more than necessary.
Step 10: Let It Rest and Serve - If you have an extra 10 minutes, cover the slow cooker again and leave the chicken and rice on the Warm setting. That short rest gives the rice time to settle into the sauce and makes the whole thing extra creamy. Sprinkle with chopped fresh parsley if you are using it, then spoon generous portions into bowls and get dinner on the table while everything is hot.