Preheat oven to 350F. In frypan, brown meat, stirring till light brown & crumbly. Add onions, celery & green pepper. Cook for 3 min. Add tomatoes & simmer a few minutes. Add salt & pepper. Cook pasta; drain. In buttered 2 qt casserole, combine pasta, sauce & blue cheese. Sprinkle grated cheese on top. Bake in a 350F oven for 20 min.