
In a large dutch oven, heat olive oil over medium-high heat and add the onion, carrots, celery, mushrooms and thyme. Season with ½ teaspoon salt and ¼ teaspoon pepper. Cook, stirring occasionally, for 8 to10 minutes, or until the vegetables have softened and the mushrooms are no longer giving off moisture.
Add rice and toast for 1 to 2 minutes, or until it smells nutty. Add chicken stock and chicken breast and bring to a boil. Season with the remaining salt and pepper. Reduce heat to a simmer, then cover and cook for 30 minutes. Remove chicken from the pot and place on a cutting board. Shred with two forks.
Continue cooking the soup for 15 minutes more, until the rice is tender. Return the shredded chicken back to the soup and stir to combine.
Add 1 cup water and white beans to a high-speed blender and process until smooth. Add bean mixture to the pot and cook for 5 minutes, then season to taste and serve.