Preheat your oven to 350°F (175°C).
In a skillet, brown the ground beef over medium heat. Drain excess fat.
Add chopped onions and sauté until translucent.
Stir in garlic powder, mustard, Worcestershire sauce, salt, and pepper.
Add diced tomatoes and beef broth; bring to a simmer.
Cook elbow macaroni according to package directions until al dente; drain.
Combine the cooked macaroni with the beef mixture.
Transfer the mixture to a greased baking dish.
Top with shredded cheddar cheese.
Bake in the preheated oven for 20-25 minutes, until cheese is bubbly.