Shortbread
["3 sticks butter, at room temperature", "1 heaping c. confectioners sugar", "1 egg yolk", "4 c. all-purpose flour, sifted"]
["Heat oven to 300\u00b0.", "Line pans with double layer of brown paper. Do not grease.", "Sift sugar; knead in butter (use on hand it is messy!).", "Add egg yolk; mix in.", "Add flour one cup at a time; knead until smooth.", "Divide into 3 (8 or 9-inch) pans.", "Pat out with hand to 1/4 to 1/2-inch thickness.", "Prick all over with fork.", "Crimp edges and mark lightly with knife.", "Bake for 45 minutes to 1 hour. Shortbread should be very pale."]
["butter", "confectioners sugar", "egg yolk", "all-purpose flour"]