Cook the beef in a 12-inch skillet over medium-high heat until well browned, stirring often to separate meat. Pour off any fat.
Stir the sauce and cream cheese in the skillet. Reduce the heat to low. Cook for 3 minutes or until the cream cheese is melted, stirring often.
Place the spaghetti into a large bowl. Add the beef mixture and toss to coat. Sprinkle with the Parmesan cheese.