Set all of your ingredients out, make sure the butter and flour are at room temperature.
Start by sifting together the dry ingredients. I usually add my dry ingredients to a medium bowl and then give them a quick stir with a whisk.
3 cups all-purpose flour, ¾ cup black cocoa powder
Add the butter, sugar, the salt to your stand mixer, fixed with a paddle attachment. Beat the butter and sugar until it is soft and creamy.
1 ¾ cup unsalted butter, 1 ½ cup granulated sugar, 1 tsp kosher salt
Add the egg yolks one at a time.
3 egg yolks
Add the vanilla. Beat again and then scrape down the sides and beat one more time.
1 tablespoon vanilla extract
Add all of the dry ingredients in at once. Turn the mixer on low. Beat very slowly until the mixture becomes crumbly.
3 cups all-purpose flour, ¾ cup black cocoa powder
OPTIONAL: Mix in chocolate chips here, if you are using them.
5 ounces bittersweet Chocolate
Scrape all of the cookie dough onto the countertop and then press it together. Divide the dough into four equal portions and make four eight-inch logs. The logs can be round or rectangular.
Wrap each log in plastic wrap and chill for at least four hours and up to overnight.
When You're Ready to Bake
Preheat the oven to 350℉.
Line your cookie sheets with parchment paper.
Slice each log of cookie dough into approximately 12 slices. They will be a little bit fatter than a quarter inch.
Bake the cookies for 14 to 18 minutes. Watch closely as oven temperatures vary.
Remove the cookies from the oven, rest for 2 minutes. Then cool on a cooling rack until they are room temperature.
Store in an airtight container.
RECIPE TIPS
Ingredient Notes
Unsalted Butter. Use European-style unsalted butter, which has a higher butterfat content than American butter.
Sugar. Granulated sugar. Superfine sugar is a good choice here because it melts into the butter more quickly.
Salt. Always use Kosher or fine sea salt for baking.
Egg yolks. Egg yolks help to refine this dough and give it a more tender crumb.
Vanilla. Use a high-quality vanilla extract.
All-purpose flour. You can also use gluten-free flour in this recipe. I've had good success with King Aurthurs One-to One(affiliate link)
Cocoa powder. Cocoa powder will be replacing some of the flour that would be in a traditional shortbread cookie. Use whatever cocoa powder you like. I've chosen dutch process or alkalized darker cocoa powder. The flavor is similar to Oreos.
How To Tell If They're DoneTouch the edges, and they should feel firm and crispy. The middle of the cookies will still feel slightly soft but should feel like they have a crust on them. They will crisp up as they cool.Because the cookies are dark, you can't really see if they are browned. I use this "feel" test to figure out if they are done or not.