WHITE SAUCE:

In a 1-quart saucepan, melt butter and add flour. Cook on medium heat until the flour thickens and pulls away from the sides of the saucepan.

Gradually pour milk into the flour, stirring constantly. Add salt. The mixture should thicken, resembling a thick pudding. Stir constantly to prevent lumps. Set aside off the heat until ready to use for the soup.