Heat 2 T. olive oil over medium heat in a large stockpot or Dutch oven. Add onion and sauté 2 minutes until just beginning to soften. Add carrots, celery (including leaves) and thyme and sauté 4 minutes.
Add chicken, salt, pepper and 4 cups chicken stock. Partially cover and simmer for 20 minutes or until chicken is cooked through and vegetables are tender.
While soup is simmering, cook Fideo according to package directions in remaining broth until al dente. Reserve 2 cups of cooking liquid before draining pasta. Drain pasta and transfer to a medium bowl and toss with remaining olive oil. Cover and set aside.
Just before serving, add Fideo to Dutch oven. Stir and remove from heat.
Add lemon zest, lemon juice, nutmeg. If soup is too thick, add a little bit of the reserved cooking liquid to desired consistency.
To serve, divide Fideo among individual serving bowls and top with hot soup. Add freshly grated Parmesan cheese.
Garnish with additional fresh cracked pepper and fresh parsley and thyme if desired. Serve with hot crusty bread and/or a crisp, garden salad for a light and delicious meal. Enjoy!