Heat oil in a large Dutch oven over medium heat. Add the onions, carrots, and celery. Sauté for 8–10 minutes. This "mirepoix" (the French term for this veggie trio) needs time to release its natural sugars, which forms the flavor foundation of the soup.

Add the minced garlic and dried thyme. Stir for only 30 seconds until the garlic is fragrant. This prevents the garlic from becoming bitter while waking up the oils in the dried herbs.

Pour in the chicken broth. Add the shredded rotisserie chicken, bay leaves, and salt. Bring to a boil, then immediately reduce to a simmer. Cover and let it cook for 20 minutes to allow the vegetables to become tender and the chicken to infuse the broth.

Add the egg noodles directly to the pot. Simmer uncovered for 8–10 minutes. Cooking them uncovered allows the starch to thicken the broth slightly, giving it that "homestyle" body.

Just before serving, stir in the fresh lemon juice. The acidity doesn't make the soup taste like lemon; instead, it acts as a "highlighter" for the savory salt and chicken flavors.

Remove the bay leaves. Serve in deep bowls with a heavy sprinkle of fresh parsley.