1/2 c. butter
1/4 c. brown sugar
1 egg yolk
1/2 tsp. vanilla
1/4 tsp. salt
1 c. flour
1 egg white
3/4 c. nuts, finely chopped

Cream butter, brown sugar, egg yolk, vanilla and salt together until light and fluffy, stir in flour. Chill dough, if necessary, for easier handling. Shape into 1 inch balls, then dip into slightly beaten egg white and roll in the chopped nuts. Place 1 inch apart on ungreased cookie sheet. Bake at 375 degrees for about 5 minutes, then remove from oven and place thumbprint in middle of cookie. Return to oven for about 8 minutes more. Cool, fill thumbprint with preferred icing.