Generously salt and pepper chicken thighs. In a large skillet over medium-high heat, using the oil, brown chicken breasts on both sides; remove to a platter and set aside. Reserve 1 tablespoon of the cooking oil in the skillet and cook the carrots, celery, and onion until mixture starts to brown. Add the tomato paste, thyme, garlic, and red pepper flakes cooking until fragrant, about 30 seconds.
Stir in 1 cup of the chicken broth scrapping any dripping from the bottom of the pan and pour the mixture into the slow cooker. Add bay leaves and remaining chicken broth to the slow cooker and add the chicken thighs to the mixture.
Salt and pepper the chicken breast, wrap breast in aluminum foil and place foil packet on top of the soup mixture.
Cook for 4 – 6 hours or until chicken is fall off the bone tender. Remove the chicken breast and thighs from the slow cooker and place a platter too cool.
Cook noodles according to package directions; drain.
While noodles are cooking using a fork shred chicken into bite-size pieces discarding the bones; add the chicken back to the slow cooker. Remove bay leaves, mix in the noodles, peas, and parsley and continue cooking until heated through.