Personally, adding cinnamon is my favorite, but other options include adding expresso or chile powder.
The second batch, I rolled them carefully in the sugar and baked them. However, during the rolling and shaping, the cookies had warmed up, so when I took them out, they were normal uncracked chocolate cookies with wimpy powdered sugar on top.
At this point, I wanted to get a hammer and crack them myself.
The third batch, I did some quick online research. Apparently to crack, they have to be cold. Heat expands things -- basic physical science from undergrad, right? Fine, fine I'm a logical cook applying evidence based science. So I chilled the batter in the freezer, then rolled them. But I was too slow again, and they were too soft, so I had to put the entire tray with the shaped balls in the fridge overnight.
Finally, after waiting forever, I was able to pop them in the oven cold and voila, they came out cracked. To enhance the cracking, when they come out of the oven, gently press down on them to make them spread out. The cookies won't look done, but cookies continue to bake as they cool (rookie mistake to overbake!)
1 cup unsweetened cocoa powder
1 cups white sugar
1/2 cup vegetable oil
2 teaspoons vanilla extract
2 cups all-purpose flour
2 teaspoons baking powder
1 teaspoon espresso powder
1/2 teaspoon salt
1 cup confectioners’ sugar
In the bowl of an electric mixer fitted with the paddle attachment (though you can do this with a wooden spoon, too) beat together the cocoa powder, white sugar, and vegetable oil until it comes together into a shiny, gritty, black dough of sorts.
Add the eggs, one at a time, mixing for 30 seconds each. Add the vanilla and beat in thoroughly.
In a separate bowl, whisk together the flour, baking powder, salt, and espresso powder if using. Mix into the chocolate mixture on low speed until just combined. Do not overbeat. Cover the dough with plastic wrap and chill the dough for four hours or overnight.
Preheat the oven to 350°F and line two baking sheets with parchment paper. Place the confectioner's sugar in a wide bowl. Using a rounded teaspoon get clumps of the chilled dough and roll them into 1-inch (2.5 cm) sized balls using your hands. Roll the balls in the confectioner's sugar and place on the cookie sheets (you should be able to get 12-16 on each sheet). Bake for 10-12 minutes. Allow to cool a minute or two on the sheets before transferring to a wire rack to cool completely