Preheat oven to 375 degrees F.

Cook macaroni according to package directions.

Meanwhile, heat milk and butter in a medium saucepan over medium heat. Gradually whisk in flour, salt and dry mustard and simmer for 1 minute, whisking occasionally.

Remove from heat; stir in 2 cups of the Cheddar cheese until melted. Add drained macaroni to saucepan and toss with cheese sauce. Transfer mixture to an 8-inch or 9-inch square baking dish. Sprinkle 1/2 cup Cheddar cheese on top (optional).

Bake uncovered until hot and bubbly, about 20 minutes. Let stand 5 minutes before serving.

Recipe Courtesy of the American Dairy Association (I Love Cheese).