Heat oven to 325°F. Fold 1 sheet of foil in half lengthwise. Fold the double-thickness foil crosswise into 1-inch pleats to make an "accordion-pleated" pan. Place on ungreased cookie sheet. Repeat with second sheet of foil.
In large bowl, combine margarine and sugar; beat until light and fluffy. Add vanilla and eggs; beat well. Lightly spoon flour into measuring cup; level off. Add flour and salt; mix well. Stir in walnuts. Drop rounded teaspoon of dough into each fold of foil. (Dough spreads during baking to form 4 1/2 to 5-inch long cookies.)
Bake at 325°F. for 18 to 26 minutes or until golden brown. Remove cookies from foil; cool completely. Turn foil over for second baking.