Combine your butter, egg,egg yolk, and vanilla, mixing it until it's light and fluffy.
Add in the dry ingredients, slowly, mixing thoroughly until combined.
Whisk a combination of cocoa and white flour to dust your counter top and it won't show up on the cookies as crazy. The dough will be more sticky, but sometimes we just don't have 45 minutes to waste! If you like colder dough to handle which in theory is less sticky, place the dough on wax paper large enough to fold over itself. Proceed to fold the wax paper over, and give it a squish to flatten it. The thinner the dough, the less time it takes to chill it.
Throw it into the fridge for 45 minutes or so.
Roll out to the thickness you desire. Thin gets you a crispy little tasty chocolate cookie, thicker gets you a chewier cookie. Chose your poison.
Bake at 350 degrees for 8-10 minutes, until they are slightly undercooked.
Cool on the tray, then move.
The above is the base for the icing, in order to get thinner icing I added a little more milk until I could dip my cookies into the icing, and let them drip off, getting this beautiful glazed coating below. Do NOT put in more corn syrup, it will never harden and set properly. So add milk very little by little until you get the consistency you need.