Cook the rotini in salted boiling water according to package instructions until al dente. Drain and set aside.

In a large skillet over medium heat, brown the ground beef, breaking it up as it cooks. Add diced onion and cook until translucent (about 5 minutes). Season with salt and pepper.

Stir in minced garlic and sauté for another minute until fragrant.

Mix in ketchup, mustard, and beef broth; simmer for about 5 minutes.

Combine cooked pasta with the beef mixture until well coated. If necessary, add more broth for desired consistency.

Sprinkle shredded cheddar cheese on top; stir until melted and creamy. Serve immediately.