Fill a pot with 2 cups stock and bring to a boil over high heat. Season with salt and pepper. Add rice and bring back to a boil. Once the rice is boiling, lower heat to medium-low to simmer.
Cover and continue to cook until all the liquid has been absorbed and the rice is soft and fluffy, 10 to 12 minutes.
Remove from heat and uncover. Fluff with a fork (cover) and set aside.
Place a large pot over medium-high heat. Add butter. Once butter has melted add onion, celery, and carrot and sauté for 3 to 4 minutes.
Lower heat to medium and add garlic and herbs. Season with salt and pepper. Sauté for 3 to 4 minutes.
Add stock and thighs and bring to a boil. Season with salt and pepper.
Lower heat to medium and simmer for 15 to 20 minutes or until chicken has cooked through.
Remove chicken thighs from pot and transfer to a bowl. Once cool enough to handle, shred with two forks (or your hands).
Stir chicken and rice into soup and season with salt and pepper.
Simmer for 5 minutes and ladle into bowls. Top with more fresh herbs. Serve with crusty bread.