Melt butter in a large pot or Dutch oven over medium heat. Add the onions, carrots, celery, and garlic. Cook, stirring every few minutes, until the vegetables begin to soften, 5 to 6 minutes.

Stir in the flour and cook, stirring it around the pan, for about 2 minutes.

Add the thyme and bay leaves, then continue to stir while pouring in the chicken stock. Bring the soup to a low simmer, then taste it and adjust the seasoning with salt and pepper as needed.

Submerge the chicken thighs in the soup so that the broth covers them. Bring the soup back to a low simmer, then partially cover the pot with a lid and cook, stirring occasionally, until the chicken thighs are cooked through and tender, about 20 minutes. Transfer the cooked chicken to a plate to cool for a minute.

Stir the noodles into the soup and cook until done, 6 to 10 minutes, depending on the type of noodles used.

While the noodles are cooking, shred the chicken into strips or dice it into cubes.

Slide the chicken back into the pot. Add the cream and parsley, then taste the soup once more. Adjust with more salt and pepper as needed.