Place the chicken, onion, garlic, bay leaf, and chicken broth in a wide cooking pot. Bring to a boil over medium-high heat, then skim off and discard any foam that rises to the surface.
2 lbs bone-in chicken thighs and drumsticks, 1 pieces medium yellow onion, 3 cloves garlic, 1 pieces dried bay leaf, 7 cups low-sodium chicken broth
Reduce the heat to low. Cover the pot and simmer gently for 20 minutes.
Add the carrots and celery. Cover and continue simmering for 10 minutes, or until the chicken is cooked through and registers at least 165°F in the thickest part.
2 pieces medium carrots, 2 stalks celery
Remove the chicken from the pot and let it cool enough to handle. Discard the bay leaf. Pull the meat from the bones and shred it, then discard the bones.
2 lbs bone-in chicken thighs and drumsticks, 1 pieces dried bay leaf
Season the broth with the ground black pepper. Taste it, then add salt as needed.
1/2 teaspoon ground black pepper, Salt
Bring the broth back to a gentle boil. Add the rotini and cook according to the package directions until al dente.
1 1/2 cups rotini
Return the shredded chicken to the pot during the last 2 minutes of cooking. Stir in the parsley once the pasta is done.
2 lbs bone-in chicken thighs and drumsticks, 2 tablespoons fresh parsley
Transfer the chicken soup to individual bowls and serve hot.