Nazis are infamous for their heinous wartime tactics and plots. Now, assassinating explosive chocolate can be added to that list, as revealed by a 60-year-old letter stamped “Secret.”

The Telegraph reports:

Giving a new meaning to the dessert name “death by chocolate”, Adolf Hitler’s bomb makers coated explosive devices with a thin layer of rich dark chocolate, then packaged it in expensive-looking black and gold paper.

German secret agents planted in Britain planned to place the “chocolate” amongst other luxury items in the War Cabinet’s dining room where Winston Churchill often hung out. After being unwrapped and tampered with, seven seconds later the sweet slabs of destruction would detonate and kill anyone within several meters of their chocolatey impact.

But the plot was foiled by British spies who discovered the chocolate was being made and tipped off one of MI5’s most senior intelligence chiefs, Lord Victor Rothschild, before the wartime prime minister’s life could be endangered.

Lord Rothschild got busy warning the Brits to be on the lookout for exploding candy bars. He typed up a letter on May 4, 1943, and sent it to an illustrator friend, Laurence Fish, asking him to draw up poster-sized depictions of the nefarious candy. Years later, Mr. Fish’s wife uncovered the correspondence while sorting through her husband’s possessions after his death in 2009.

The letter, marked “secret”, reads: “Dear Fish, I wonder if you could do a drawing for me of an explosive slab of chocolate. “We have received information that the enemy are using pound slabs of chocolate which are made of steel with a very thin covering of real chocolate. “Inside there is high explosive and some form of delay mechanism…When you break off a piece of chocolate at one end in the normal way, instead of it falling away, a piece of canvas is revealed stuck into the middle of the piece which has been broken off and a ticking into the middle of the remainder of the slab.”

Lord Rothschild also reportedly included a very poor drawing of the device in his letter.

Luckily, the diversion worked. The plot was foiled, and today the only chocolate antagonism between Germans and British is over whether Milka or Cadbury is the more delicious treat.

More from Smithsonian.com:

Becoming a Chocolate Connoisseur

UK vs USA: A Cheap Chocolate Showdown