Melt the butter (or your choice of oil) in a large pot or Dutch oven over medium heat. Toss in the chopped onions, carrots, and celery. Give it a good stir and let them soften up for about 5 to 6 minutes.
Stir in the garlic, bay leaves, and thyme. Cook for about a minute, just enough to wake up the flavors.
Pour in the chicken stock and bring it to a gentle simmer. Taste the soup and season with salt and pepper.
Nestle the chicken thighs into the broth, ensuring they're fully submerged. Cover the pot partially with a lid and let it simmer gently for about 20 minutes, stirring occasionally. Top up the broth if necessary.
Once the chicken is cooked, scoop it out onto a plate. Stir the noodles into the soup and cook them until tender—usually 6 to 10 minutes, depending on the type of noodles you use.
While the noodles cook, shred or dice the chicken into bite-sized pieces. Add the chicken into the pot and stir.
Taste the soup again and add more salt or pepper to the seasoning. Stir in the fresh parsley for a pop of color and freshness.