Choc Whirl is a new variety of Kit Kat, the world-famous chocolate block and bar from Nestle. Unlike its brother Choc Mint Whirl, Choc Whirl is only available in the large 170g block (whereas you can find Choc Mint in the block and medium and king size bars). They were released together a few months back. I also believe Choc Whirl is unique to Australia as well.