To make the cookies, in an electric stand mixer fitted with the paddle attachment, add the butter and C&H® Golden Brown Sugar and mix on medium for about 4 minutes, or until well blended. With the mixer on low, add in the egg yolk and vanilla extract and run for 2 minutes more or until completely blended. Scrape down the sides and bottom of the bowl to make sure everything is well incorporated.
In a medium bowl, whisk together the flour, cocoa powder, baking powder, and salt and baking powder. Add this to the butter mixture and run on low for 2 minutes, or until everything is combined and the dough has come together.
Separate the dough into two chunks and shape each into a disc. It’s a little messy, but you can do it. Wrap tightly in plastic wrap and stash in the fridge for 30 to 60 minutes to rest. Don’t chill for longer, or it will be too difficult to roll out. If this happens, let the dough come close to room temperature before attempting to roll out. You want it soft enough so that it rolls out without cracking, but cool enough that it’s not too sticky.
Preheat the oven to 350°F (177°C) and cover several baking sheets in parchment paper. Let the dough sit for 10 minutes or longer to soften when removing from the fridge and place it between two layers of parchment paper lightly coated in unsweetened cocoa powder. If you have a silicone baking mat, place it underneath the parchment to keep it from sliding on the counter. Roll the dough to 1⁄4-inch (0.7-cm) thickness. Don’t go too thin. Periodically check to make sure the dough isn’t sticking and sprinkle lightly with more cocoa powder when it does. If the dough becomes sticky, place in the freezer to firm up a bit. Once it’s rolled out, I like to chill it in the freezer one final time – it will make getting nice, clean cuts easier.
Using a 1 1⁄2-inch (3.7-cm) cookie cutter, cut as many cookies out of the rolled dough as you can. Place the cookies on the parchment covered baking sheet, leaving 1 inch (2.5 cm) between cookies. Repeat with the other disc of dough, re-rolling the dough and cutting cookies until done.
Place the cookies in the freezer for 15 to 20 minutes or the fridge for 30 to 40 minutes, and then take them directly from the freezer to the top rack of the oven and bake for 9 minutes. It’s crucial not to overbake these. Let them cool for 5 minutes on the baking sheet and then transfer to a rack to finish cooling.