Cook macaroni according to package instructions.
Coarsely shred cheese and season breadcrumbs with white pepper.
Combine macaroni with corned beef and place in a greased baking
Melt butter or margarine in a saucepan and blend in flour,
mustard and salt. Add milk and cook, stirring constantly until
thickened and smooth. Pour over macaroni and corned beef mixture.
Sprinkle with cheese then breadcrumbs. Bake at 180°C (350°
F) for 30 minutes or until brown and bubbling. (The breadcrumbs
may also be seasoned with garlic powder and/or paprika).