Heat oven to 375 degrees. Spray non-stick cookie sheet with non-stick cooking spray. Grind pecans in blender or food processor until consistency of coarse meal. Mix 1/2 cup of the ground pecans and remaining ingredients except egg whites and vanilla. Stir in egg whites and vanilla until stiff dough forms.
Sprinkle remaining ground walnuts on lightly floured surface. Divide dough into 4 equal parts. Use dash of vanilla if dough seems to need extra liquid. Roll each into rope, about 14 inches long and 3/4 inch thick, on walnuts. Place on cookie sheet. Bake 20 minutes. Remove from oven; cut diagonally into 1-inch thick slices. Reduce oven temperature to 225. Bake 15-20 minutes longer or until crisp.
Makes about 4 1/2 dozen cookies.