Cook and drain macaroni.
In large skillet, quickly saute onions, celery and green peppers in olive oil. Add tomatoes, basil and oregano. Mix thoroughly. Add cooked macaroni to skillet and mix thoroughly.
Melt butter in saucepan. Mix in flour until blended well. Add milk and slowly bring to a boil. Add nutmeg, cayenne pepper and cheese, stir in continuously until all the cheese is melted.
Pour macaroni mixture into baking dish. Pour cheese sauce over it. Sprinkle with Parmesan cheese evenly over the top.
Place under broiler for 5-10 minutes until top is browned.