The Ultimate Butter Cookies
-Mix in the egg yolk until well incorporated.
-Add the flour and mix just until incorporated.
-Scrape onto a lightly floured board and knead a few times, just until the dough smooths out.
-Turn onto a sheet of plastic wrap and roll into a log, wrap up and refrigerate for several hours or freeze.
-Line your baking sheets with parchment.
-Slice the dough into slices about 1/8" thick and place them on the sheets about an inch apart.
-Bake until JUST beginning to turn golden around the edges, about 16-20 minutes.