The ad agency teamed up with two artists to create 'Dan & Dave's Chocolate Factory' (named after the agency's founders), which pops out an edible treat in exchange for a charitable donation.
Little and big kids alike can insert £1 into the agency's chocolate coin factory and watch the fantastical array of bells, whistles, cogs and wheels come to life.
In return, the working copper and brass factory proffers a specially designed gold chocolate coin...and a warm, fuzzy feeling inside. All the money collected goes towards building a playground for Millfields Community School.
Laurie Howell and Toby Treyer-Evans were the creatives behind the contraption that rather unsubtly fuses the feel-good trinity of Christmas, chocolate and charity. They worked with sculptor Ben Hughes and artist Joshua T Howell.
You can catch their window display at the agency in Hanbury Street until 6 January. But if you can't be bothered to travel all the way to east London, you can just sit at your desk and watch the machine in action here.
But that wouldn't be very festive of you, would it?