Place the rotisserie chicken in a large pot and add two 32oz. boxes of chicken stock and then add enough water to cover the chicken.
Add 2 teaspoons of salt and 1 teaspoon of black pepper, or to taste.
Bring the pot to a boil over medium heat. Once boiling, reduce the heat to medium and let it simmer for one hour or until the meat is falling off the bone.
Remove the chicken from the pot and set it aside to cool.
Add the bag of frozen egg noodles to the pot with the remaining chicken stock. Stir to separate the noodles and bring to a low boil over medium to medium-high heat. While the chicken is cooling, peel and dice the carrots, celery, and onions.
Once the noodles start to boil, add the chopped carrots, celery, and onions to the pot. You can add more liquid with more chicken stock if needed. The liquid will evaporate while boiling the chicken so add as needed or you can add more water if you don't have more chicken stock and add more of the bouillon flavoring.
Debone the cooled chicken and break into small pieces. Don't over shred the meat and add the chicken back into the pot and stir every so often.
Add about half of the container of chicken flavored Better than Bouillon Seasoning or 4-6 chicken bouillon cubes to the pot. This is also to taste so make sure to taste the broth to make sure it has enough flavor. Add more bouillon if needed. You want a rich chicken flavored broth.
Stir everything together and let it simmer for about 15-20 minutes, or until the carrots are fork-tender and the noodles are fully cooked.
Taste the broth and adjust the seasoning with more salt and pepper or bouillon if needed.
Serve hot and enjoy your homemade chicken noodle soup!