Twinkies and cheezwhiz would survive a nuclear blast ;)
Scientist: Hey, Doctor Oppenheimer, come take look at this. It's... It's some kind of spongy, yellow, almost cake-like material. And it's built up on almost every vertical rock face within 2 miles of the epicenter. [pauses, removes a piece of the material from a rock face and inserts it in to a small device] Hmmmmmm. That's strange. Even though back-ground environmental radiation levels are still quite high, this... this... "sponge cake" doesn't appear to carry ANY residual radiation. What do you suppose it is?
Oppenheimer [licking his lips]: I have no idea, Dr. Twinklestein, but it sure is DELICIOUS! And it's got a cream filling!