Heat a large skillet over medium-high heat. Add the ground beef and onion and sprinkle with ½ teaspoon each salt and pepper. Cook until the beef is browned and the onion is tender. Drain, if necessary.
Stir in the tomato paste, chili powder, and garlic powder and cook until combined.
Add the beef broth and bring to a boil. Stir in the macaroni. Return the mixture to a boil.
Cover, reduce the heat to low, and cook for 13 minutes or until the pasta is tender, stirring occasionally.
Whisk the cornstarch with 1 tablespoon cold water in a small bowl. Whisk into the sauce. Stir in the cheese until it melts. Remove the skillet from the heat and let the mixture stand until thickened and creamy. Sprinkle with parsley before serving, if desired.