Scotch Shortbread
["1 c. butter", "1/2 c. brown sugar", "1 egg yolk", "1 tsp. vanilla", "2 c. sifted flour", "1 tsp. baking soda"]
["Cream butter and add sugar.", "Blend thoroughly.", "Add egg yolk and vanilla.", "Sift flour and baking soda and mix well with first mixture.", "Spread in ungreased pan and then prick deeply with a fork.", "Bake in a 250\u00b0 moderate oven for 25 minutes or until golden brown."]
["butter", "brown sugar", "egg yolk", "vanilla", "flour", "baking soda"]