1/2 c. butter
1/2 c. sugar
1 egg yolk, slightly beaten
1/4 c. flour
1/2 tsp. salt
1/2 tsp. vanilla

Cream butter and sugar until light. Add egg yolk; mix well. Add flour, sifted with salt. Mix. Roll dough in small balls, dip in unbeaten egg whites and roll in finely chopped nuts. Place on buttered baking sheet and press down center of each with thimble. Bake at 325 degrees for 5 minutes. Remove from oven and press down again with thimble and return to oven for about 10 to 15 minutes. Remove from oven and fill indentation with preserves while still warm.