Saute ground beef, onion and green pepper until meat is browned.
Add tomatoes and worcestershire sauce. If you use more than one pound of ground beef, add an extra can of tomatoes. Bring to a boil and then reduce to a simmer.
Cook macaroni according to directions on package.
Simmer sauce until macaroni is complete. Do not start the macaroni until the sauce has started to simmer for more flavor.
Combine the sauce and the macaroni and pour into a baking dish.
Cover with Velveeta cheese or American cheese slices.
Cook in oven at 350 degrees for 45 minutes, or until the cheese is browned and melted.