In a large skillet over medium heat, cook the ground beef, onion, and green pepper until the beef is no longer pink. Drain off the excess fat.
Stir in the diced tomatoes, tomato soup, water, Worcestershire sauce, garlic powder, oregano, salt, and pepper. Simmer for 10 minutes.
Meanwhile, cook the macaroni according to package directions.
Preheat the oven to 350 degrees F (175 degrees C).
In a 9x13 inch baking dish, layer half of the cooked macaroni, beef mixture, and cheese. Repeat the layers. Bake in preheated oven for 30 minutes, or until cheese is melted and bubbly.
Interesting Facts
This casserole can be made ahead of time and refrigerated or frozen for later use.
Feel free to add other vegetables to the beef mixture, such as mushrooms, zucchini, or bell peppers.
For a bit of a kick, add 1/4 teaspoon of cayenne pepper to the beef mixture.