1/2 c. soft butter
1/4 c. brown sugar
1 egg yolk
1 c. sifted flour
1/4 tsp. salt
1/2 tsp. vanilla

Cream together butter, sugar, egg yolk and vanilla. Sift flour and salt; mix well. Roll into 1" balls. Dip in slightly beaten egg white. Roll in finely chopped nuts (3/4 cup). Place about 1" apart on ungreased baking sheet. Bake 5 minutes. Remove from oven, quickly press thumb gently on top of each cookie. Return to oven and bake 8 minutes longer; cool. Fill the thumb print with jelly, fruit or tinted sugar icing. Oven temperature, 375 degrees.

Makes 2 dozen.