Preheat oven to 450 degrees Fahrenheit. Place chicken breasts in a single layer in a baking dish. Rub with olive oil, then season with salt, pepper, and 1/3 of the sprigs of thyme. Roast until chicken is tender but not dry. Shred the chicken in large pieces when cool enough to handle. While chicken is cooking, place the chicken broth in a Dutch oven. Add the carrots, leeks, cheese rind and a dash of salt. Bring to a boil and reduce the heat to a simmer and cook for approximately 25 minutes until the vegetables are tender, adding several of the sprigs of thyme during the last 5 minutes of cooking.
Add the lemon garlic orzo and the shredded chicken to the pan and return to a boil, reduce heat to a simmer and cook for 5 to 7 minutes or until orzo is tender yet firm. Remove cheese rind, ladle into bowls, and serve with crackers or wild rice baguette.