In a large skillet, cook beef and onion over medium heat until meat is no longer pink; drain. Add the water, tomato paste, salt and garlic powder. Bring to a boil. Reduce heat; cover and simmer for 5-7 minutes or until heated through.
In a small saucepan, melt cream cheese over low heat, stirring constantly. Gradually stir in milk and Parmesan cheese until blended.
Place noodles in a greased 13-in. x 9-in. baking dish. Spread meat sauce over noodles. Spoon cream cheese mixture evenly over top. Bake, uncovered, at 350° for 30-35 minutes or until heated through.