Cream together butter and powdered sugar and cocoa.

Mix in oil, egg and vanilla.

Blend in flour, baking powder and salt.

Mix until the dough forms a ball and pulls away from side of mixing bowl.

Portion out a tablespoon and a half of cookie dough for each cookie, roll it into a ball and then, make the sides flat by pushing it onto the counter (almost like slapping it onto the counter) to shape them into irregular square shapes.

Bake at 400° for 7 minutes.

Cool completely before icing.

Write the word Coal on some of the cookies with Royal Icing (recipe here)

Allow icing to dry completely before stacking.