Cook chicken as desired until no longer pink (or use leftovers if you have some on hand); shred or cut into bite-sized pieces.
Finely dice carrots, potatoes, celery, and onion. In a soup pot, heat a small drizzle of olive oil over medium heat. Add veggies to the pan and cook over medium heat until crisp-tender.
Add garlic, and cook 1-2 minutes longer until fragrant.
Pour in 3 cups of the chicken stock and add the cooked chicken. Bring mixture to a simmer over medium heat and let simmer for 15-20 minutes until vegetables are completely tender.
Homemade Noodles: While the soup is simmering, go ahead and start making the noodles. Make sure you use the tightest setting on the pasta machine so the fettuccine comes out super thin.Store bought Noodles: Prepare according to directions on package.
Add the cooked noodles to the soup pot and serve.
Notes
To make the noodles from scratch, you can follow this dough recipe and then run through a pasta machine set super thin.