This easy recipe makes the best chocolate sugar cookies with a soft and chewy texture and a cracked surface. These are very popular at Christmas time on Christmas cookie platters and dessert buffets.
Preheat the oven to 350 °F (175 °C). Line large baking sheets with parchment.
In a medium bowl, whisk together the flour, cocoa powder, baking soda and salt. Set aside.
In the bowl of an electric mixer fitted with the paddle attachment, cream together the remaining butter the brown sugar, and the 100 grams (½ cup) of granulated sugar until it is light and fluffy (takes at least 3 minutes). Scrape down the sides of the bowl and mix again.
Add the egg and vanilla, and beat them in until the mixture is smooth and light.
Add the flour mixture slowly, on low speed and mix until the dough is combined.
Put the remaining 50 grams of sugar in a shallow bowl.
Roll scoops of cookie dough into balls and then coat them in sugar. Place each sugar-coated scoop of dough on a cookie sheet, spacing them out every 1.5 inches. You should be able to fit 8 per sheet pan.
Bake the cookies for 12 minutes or so, until they have puffed and cracked and are just beginning to set in the middle. Let cool for 5 minutes to firm up before transferring to a rack to cool completely.
Notes
Use Dutch-processed cocoa powder, which has a darker colour and richer flavour. Natural cocoa powder is more acidic and may affect the texture and appearance of these cookies.
If your chocolate cookie dough is too soft, you may chill it briefly for about 30 minutes. I have never needed to, but you may have to especially if your kitchen is warm.
Use a ¾ ounce scoop to evenly portion out perfect scoops of dough. You can smooth them out by rolling them briefly between your palms.
Do not overbake these cookies because they will dry out.
These cookies are best eaten within 2–3 days because they may dry out and become more crispy.