1In 10-inch skillet, cook beef and onion over medium-high heat 5 to 7 minutes, stirring occasionally, until beef is thoroughly cooked; drain.
2Stir in hot water, milk, uncooked Pasta and Sauce Mix. Heat to boiling, stirring occasionally.
3Reduce heat; cover and simmer about 10 minutes, stirring occasionally, until pasta is tender. Stir in spinach; sprinkle with cheese. Cover; simmer about 2 minutes or until cheese is melted.