Take ice cream, plus one B-17...

American ingenuity in World War II:

According to a 1943 New York Times article . . . American airmen stationed in Britain "place prepared ice-cream mixture in a large can and anchor it to the rear gunner's compartment of a Flying Fortress. It is well shaken up and nicely frozen by flying over enemy territory at high altitudes." — Anne Fadiman, "Ice Cream," At Large and At Small 56

From what I heard about the average temperature inside my father's B-24 (aka "Willie the Wolf"), I believe it.