Place whole chicken in a large dutch oven. Lightly salt and pepper the chicken. Pour in 4 cups of chicken broth and turn heat on to medium. Cover and simmer for 90 minutes.
Check the temperature of the chicken. It is finished cooking at 165 degrees in the middle of the chicken breast near the bone. When chicken reaches this temperature, remove it from the dutch oven and allow to rest before shredding.
Strain the broth into a bowl and reserve to add back to the dutch oven after the vegetables sauté.
In the empty dutch oven, melt the butter over medium heat. Add the onions, carrots, and celery. Cook until onions are translucent. Add garlic and cook for 1 additional minute.
Add the broth that the chicken was cooked in back into the dutch oven, along with an additional 8 cups of broth, a bay leaf and rosemary.
Once the chicken is cooled enough to work with, shred the chicken and add it back to the pot.
Simmer for 30 minutes.
Add the egg noodles into soup and simmer for 12 minutes, stirring occasionally.