Hence the four-hands dinner, a dining experience that involves two chefs working together to create a special menu for a limited period. This summer has seen a bumper load, a highlight of which was Anne-Sophie Pic joining Marcel Ravin at Blue Bay in Monaco. And although this is by no means a new concept - back in 2008, Thomas Keller and Grant Achatz collaborated on what may well have been the culinary event of the decade - this fall it's in danger of jumping the shark.