Coat a Dutch oven with cooking spray; place over medium-high heat until hot. Add onion, carrot, green onions, and celery; saute until tender. Add chicken broth, potato, and rice; bring to a boil. Reduce heat, and simmer 20 minutes or until vegetables are tender. Remove from heat, and let cool 10 minutes.
Transfer mixture, in batches, to container of an electric blender; cover and process until smooth. Return mixture to pan. Stir in cheese and remaining ingredients. Cook over medium heat, stirring constantly, until cheese melts and mixture is smooth.