Cook pasta according to package directions. Drain; set aside.
Meanwhile, in a medium saucepan stir together the milk powder, onion, flour, and salt. Gradually stir in the milk until mixture is smooth. Cook and stir over medium heat until thickened and bubbly. Reduce heat to low. Add the cheese, stirring until melted. Stir in the pasta. Spoon mixture into a 1-1/2-quart casserole.
Bake, uncovered, in a 350 degree F oven about 25 minutes or until bubbly, stirring once and topping with crushed breadsticks after 15 minutes. Let stand 5 minutes before serving. Makes 4 servings.