Jam Thumbprints

2/3 cup butter
1/3 cup sugar
2 egg yolks
1 teaspoon vanilla
1/2 teaspoon salt
1 1/2 cups flour

2 egg whites -- slightly beaten
3/4 cup nuts -- finely chopped
1/3 cup raspberry jam

Cream together butter and sugar till fluffy. Add egg yolks and vanilla. Beat well then add salt and flour and mix well. Shape into 3/4" balls; dip into egg whites then roll in nuts. Place 1" apart on greased cookie sheets. Press down center of each cookie with thumb. Bake at 350 degrees for 15-17 minutes. Cool slightly. Remove from pan and cool on rack. Just before serving spoon raspberry jam into cookie indentations.