1 Beat together cocoa powder, white sugar, vegetable oil: In the bowl of an electric mixer fitted with the paddle attachment (or beat by hand with a wooden spoon) beat together the cocoa powder, white sugar, and vegetable oil until it comes together into a shiny, gritty, black dough of sorts.
2 Add eggs, one at a time, add vanilla/Kahlua: Add the eggs, one at a time, mixing for 30 seconds each. Add the vanilla and beat in thoroughly.
3 Whisk together flour, baking powder, salt, espresso powder: In a separate bowl, whisk together the flour, baking powder, salt, and espresso powder.
4 Beat dry ingredients into cocoa oil mix: Mix into the chocolate mixture on low speed until just combined.
5 Cover and chill: Cover the dough with plastic wrap and chill the dough for four hours or overnight.
6 Roll dough into balls, roll into powdered sugar, place on cookie sheet: Preheat the oven to 350°F and line two baking sheets with parchment paper or non stick foil. 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). You can roll them in granulated sugar first - this makes them a bit more crispy on the outside.
I cool them again for about 10/15 minutes before baking as they get a bit soft during rolling.
7 Bake: Bake at 350°F for 10-12 minutes. Allow to cool a minute or two on the sheets before transferring to a wire rack to cool completely.