In a large pot cook macaroni in boiling salted water until al dente. Drain well.
In a large saucepan over medium heat melt the grated Cheddar cheese, plain yoghurt, butter or margarine and tomatoes. Cook until smooth. Add salt, black pepper, basil to taste, celery seed and cooked pasta to saucepan. Stir until blended. Shut off burner and let sit for 10 minutes with lid on, stirring occasionally.