I found my Luby's cookbook - the first one published years ago
Macaroni and Cheese8 ounces (2 cups) dry elbow macaroni
2 tbs nonfat dry milk
2 tbs all-purpose flour
1 tbs butter or margarine, melted
1 and 1/4 cups boiling water
3 cups ( 12 ounces) shredded American cheese
1/4 teaspoon salt------ I never use the salt
1. cook macaroni according to package directions- drain
2. heat oven to 350
3. in large bowl, mix dry milk, flour, and butter- gradually add boiling water, beating constantly - add 1 and 1/2 cups of cheese and continue
beating until smooth and creamy - stir in macaroni - 1 cup of the remaining cheese, and salt - transfer to lightly greased 2- quart baking dish -
cover with foil
4. bake for 25 minutes
5. remove foil - sprinkle with remaining 1/2 cup of cheese - continue baking 1 minute or until cheese melts