Here's an easy recipe for butter cookies and chocolate butter cookies. Mix softened butter with powdered sugar and egg yolk in that order, then divide the dough into two portions. Add cake flour to one portion, and cake flour and cocoa powder to the other portion and mix. Pipe out cute heart shapes or individual cookies using a piping bag, then bake in the oven. These baked goods are perfect for gifts or for enjoying at home, and are recommended even for beginners.