Mix together, and divide dough in half. Add packet of coca powder to one half and mix in well.
From a roll of 11" or 12" waxed paper, tear off a sheet 18" to 24" long. Crease in half lengthwise, and cut apart into two long halves. Pat out white cookie dough to all edges on one half, and the chocolate dough on the other. Chill both to stiffen slightly. Place paper with white dough upside down on top of chocolate dough, and carefully peel paper on the white dough away. You will now have on the other paper a layer of chocolate dough topped with a layer of white dough. Pick up one long edge of the double layered dough (using paper as an aid) and roll like jelly roll. Chill for about one hour or until very stiff.
Slice thin and place on cookie sheet lined with more waxed paper. Bake for 5 minutes in preheated 350° oven. Remove cookies, waxed paper and all to cool while you reline the cookie sheet with more waxed paper to bake another pan full of cookies.
Makes from 100 to 150 cookies, depending on how thin they are.
