1 c. butter, softened
1/2 c. brown sugar
2 egg yolks (reserve whites)
2 tsp. vanilla
2 c. flour
1/2 tsp. salt
1 to 1 1/2 c. finely chopped walnuts

ICING:

4 tbsp. butter
2 c. confectioners' sugar
2 tbsp. milk
1 tsp. vanilla

Mix together butter, brown sugar, egg yolks and vanilla. Sift flour and salt and add to other ingredients. Form dough into balls. Roll in slightly beaten egg white; roll in finely chopped nuts. Place on ungreased cookie sheet; bake for 5 minutes; remove from oven, make imprint with 1/4 measuring spoon; return to oven for another 5 minutes.

Let cool. Remove from baking sheet. For icing: Cream butter until very soft, add sugar gradually thinning with milk until it is of spreading consistency; add vanilla. Beat until smooth. Fill imprints with icing.