Melt butter or margarine in skillet or saucepan. Add flour and salt, and stir until blended. Add milk to flour mixture and stir constantly until ingredients are well blended. Cook until thickened.
Add cheese and immediately remove from heat. Stir until cheese has melted. By making a sauce first, you have a much more delicious concoction.
Grease 2 or 3-quart casserole and place macaroni in casserole. Pour cheese over macaroni and mix. (I like to sprinkle lightly with paprika. It’s pretty and browns nicely.) Bake uncovered at 350 degrees for about 45 minutes to one hour until bubbly and turning brown. Be careful not to dry it out.