Begin by preparing your ingredients. Chop the carrots, celery, and onion, and mince the garlic.
Place the boneless, skinless chicken breasts in the bottom of the crock pot.
Add the chopped vegetables (carrots, celery, onion), minced garlic, and seasonings (thyme, parsley, black pepper, salt, and bay leaf) over the chicken.
Pour in the chicken broth and add the uncooked rice.
Stir to combine all the ingredients carefully.
Cover the crock pot with its lid and cook on low for 6 hours or until the chicken is cooked through and the rice is tender.
After cooking, remove the chicken breasts and shred them with two forks. Return the shredded chicken to the soup and stir.
If using, add the frozen peas and heavy cream. Stir until combined and allow to heat through for an additional 10 minutes.
Taste and adjust seasoning as desired before serving hot.