Cream together 1 1/2 cups white sugar, butter or margarine, 1 teaspoon vanilla, and eggs. Add sour cream.
Mix together 5 cups flour, 1/2 teaspoon salt, baking powder and baking soda. Gradually add to the egg-sugar mixture.
Cover and chill dough for 1 hour.
Preheat oven to 375 degrees F (190 degrees C).
Roll out on lightly floured surface to 1/4 inch thick. Cut out cookies. Bake on lightly greased cookie sheet for 10 - 12 minutes.
To Make Frosting: In small bowl, with mixer at medium speed, beat together the softened cream cheese and evaporated milk until smooth. Add 1 teaspoon vanilla, 1/8 teaspoon salt and confectioners' sugar. Beat until well blended. Color as desired and frost cooled cookies.