A soufflé was a baked entrée which required, amongst other ingredients, eggs and milk. Oswin Oswald claimed to be have been fighting the Daleks by making soufflés. She was not, apparently, very skilled at soufflé-making, because she burnt them and otherwise couldn't get them to rise properly.
However, the Eleventh Doctor — suspicious of where she could possibly be getting the milk for these creations – eventually determined that she was, in reality, making no such dishes. She was merely sublimating the terrible truth that she had been converted into a Dalek, and was hallucinating the soufflés, along with her perceived environment. (DW: Asylum of the Daleks)
