Heat oven to 350°F. In 10-inch skillet, cook beef over medium-high heat 5 to 7 minutes, stirring frequently, until brown; drain. Stir in chili powder. Stir in hot water and milk, sauce mix and uncooked pasta (from Hamburger Helper box). Heat to boiling, stirring occasionally. Reduce heat; cover and simmer 14 minutes, stirring occasionally. Remove from heat; uncover. Stir in 1/2 cup of the cheese.