In a small bowl, combine cornstarch, garlic powder, sugar, salt, paprika, and pepper. Set aside.
Heat a large skillet over medium-high heat. Brown the ground beef and onion, breaking it up with a wooden spoon, until no pink remains. Drain any excess fat.
Add milk, broth, and uncooked elbow macaroni to the beef. Stir the cornstarch and spice mixture. Bring to a boil over medium-high heat.
Once boiling, reduce the heat to a gentle boil, cover and cook for 9-12 minutes or until the pasta is cooked through, stirring occasionally. If needed, add more broth or water.
Remove from heat and stir in cheese until melted. Serve hot.