Beat margarine and sugar until fluffy. Add egg yolk and vanilla and keep beating. Add and mix in the flour, crushed potato chips and pecans.
Roll into 1 inch balls and place on ungreased cookie sheet 3 inches apart. Flatten with a glass dipped in sugar.
Bake for 12 - 15 minutes. (The cookies freeze beautifully.)
This recipe is from the Yarmouth Port Library's cookbook Cooking Along 6A. The Yarmouth Port Library is at 297 Main Street (Route 6A) in Yarmouth Port. This recipe appeared in the 2012 April issue of Cape Cod LIFE.