Place cubed chicken breasts into slow cooker pot. Top with baby potatoes, carrots, celery, onion, and garlic.
Add the chicken broth, Worcestershire sauce, tomato paste, dried thyme, dried rosemary, salt, pepper, and bay leaves.
Place lid on top and cook on the low setting for 6-7 hours or the high setting for 4-5 hours.
In the last 30 minutes of cook time, combine the cream and cornstarch together in a bowl until there are no more clumps. Stir the mixture along with the frozen peas into the stew and continue cooking to allow the stew to thicken.
Before serving, discard the bay leaves. Top with fresh parsley if desired.