Thumbprint Cookies
["2/3 c. butter", "1/3 c. sugar", "2 egg yolks", "1 tsp. vanilla", "1/2 tsp. salt", "1 1/2 c. flour", "2 egg whites", "3/4 c. pecans, finely chopped"]
["Cream butter and sugar until fluffy.", "Add egg yolks, vanilla and salt, beat well.", "Gradually add sifted flour, mixing well. Shape into 3/4-inch balls; dip in slightly beaten egg whites, then roll in pecans.", "Place 1-inch apart on greased cookie sheet. Press down center with thumb.", "Bake at 350\u00b0 for 15 to 17 minutes. Cool slightly; remove from pan and cool on rack.", "Fill with icing or preserves.", "Makes 3 dozen."]
["butter", "sugar", "egg yolks", "vanilla", "salt", "flour", "egg whites", "pecans"]