Heat the oil in a dutch oven or soup pot to medium heat. Add the onions, carrots, and celery and stir to coat. Cook for 3-5 minutes until the onions are softened. Add the garlic and ginger and stir. Cook for another 30 seconds to a minute until fragrant. Add the broth and stir in the bouillon. Add the chicken breasts, rosemary, thyme, salt, and pepper and increase the heat to bring the contents to a boil. Reduce the heat to a simmer and simmer, uncovered, for 20-25 minutes until the chicken breasts are cooked through.