In a large pot on medium-high heat, heat oil, add onions and stir for 1 minute. Add garlic, stir and then add herbs. Cook until onions have softened slightly, about 5 to 7 minutes, then add carrots and stir for a few more minutes.
Add chicken to the pot then add broth and salt and pepper, cover and turn the heat to high and allow the liquid to come to a boil. Once boiling, turn the heat to medium-low and cook for about 60 more minutes. Add the spinach and cook until slightly wilted, about 5 minutes. Serve warm.