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 .
But that wouldn't be very festive of you, would it?