Polish Tea Cakes
["1/2 c. butter", "1/2 c. sugar", "1 egg yolk, slightly beaten", "1 c. flour", "1/2 tsp. salt", "1/2 tsp. vanilla", "chopped nuts", "melted chocolate or preserves"]
["Cream butter and sugar until light.", "Add egg yolk; mix well. Add flour, sifted with salt; mix.", "Roll dough into small balls. Dip in unbeaten egg whites and roll in finely chopped nuts.", "Place on buttered baking sheet; press down center of each with thimble. Bake in a 325\u00b0 oven for 5 minutes.", "Remove and press down again with thimble.", "Return to oven for 10 to 15 minutes.", "Remove and fill indentation with preserves or melted chocolate while still warm."]
["butter", "sugar", "egg yolk", "flour", "salt", "vanilla", "nuts", "chocolate"]