1. Heat the olive oil in a large deep skillet or Dutch oven over medium-high heat.

2. Add the diced onion and ground beef. Cook for 6 to 7 minutes, breaking the beef into small pieces, until the beef is cooked through and the onion is soft.

3. Season with garlic powder, 1 teaspoon salt, and 1/4 teaspoon black pepper.

4. Stir in the tomato paste and Worcestershire sauce. Cook for about 1 minute, until the tomato paste deepens in color.

5. Add 3 1/4 cups beef broth, diced tomatoes with their juices, the remaining 1 teaspoon salt, and remaining 1/4 teaspoon black pepper. Stir well and bring to a boil.

6. Stir in the elbow macaroni. Cook over medium heat for about 10 minutes, stirring occasionally, until the pasta is tender. Add extra broth a few tablespoons at a time if the mixture gets too thick before the pasta is done.

7. Remove from the heat and stir in 1 1/2 cups cheddar cheese until creamy and melted.

8. Sprinkle the remaining 1/2 cup cheese over the top. Cover for about 3 minutes, until melted. For a browned top, place the skillet under the broiler for 2 to 3 minutes, if using an oven-safe pan.

9. Garnish with parsley or scallion, if desired, and serve warm.