In 4-quart Dutch oven melt butter over medium heat. Add celery and onion; cook and stir until onion is tender. Stir in broth, milk, and the 1 teaspoon hot pepper sauce. 2.
In bowl toss together mozzarella, 1 cup of the blue cheese, Parmesan, and flour. Add gradually to soup, stirring after each addition just until melted. Stir in three-fourths of the shredded chicken; heat through. Top with remaining chicken, blue cheese, and hot sauce. Makes 6 servings.