Take the dough out of the refrigerator and let it sit on the counter for 30-60 minutes to soften.
Roll dough into a log, about 2" in diameter. Use the bench scraper to cut off an inch off the log and flatten it with your hands. Sprinkle it with cocoa powder and run it through the widest setting on the pasta maker.
Continue running the dough through the pasta maker, decreasing the thickness each time until you've reached the desired thickness, about 1/8"-3/16" and the dough has become a sheet of chocolate.
Lay the sheet flat on the pastry mat and run the chopstick under the chocolate sheet. Pinch the chocolate above the chopstick to form a ruffle. Pull the chopstick out and run it under the chocolate sheet again, next to the first ruffle. Repeat this process until the entire sheet has been ruffled.
Repeat cutting dough off the log until all the dough is used. The chocolate ruffles will keep and harden on the counter as you continue working with the remaining dough. When all the dough has been used and all the ruffles have been formed, allow the ruffles to sit on the counter to harden for about 30 minutes before using for cake decorating.
To apply ruffles to the cake, apply a bit of frosting at the underside of the ruffle or at the unexposed end and place on the cake. It will be easy to cut through the ruffles when you're ready to cut the cake if you let the cake sit out for an hour before cutting.