Spunge was served in the episode, "The Tale of the Hatching".
Spunge (with a U instead on an O) was a dessert served by Mr. & Mrs. Taylor. They served it to the students at their boarding school, every evening. The dessert somewhat resembles a type of rice pudding. However, The Taylor's were the last of their kind of a type of Reptilian Aliens. Therefore they used this dessert to brainwash their students into waking up late in the middle of the night, while sleepwalking to help nurture and look after their many eggs.
Also this dessert keeps the person who ate it, to not remember what they did when they were sleepwalking, but it has been known to cause some of the people very bad nightmares. When Mr. & Mrs. Taylor died and all their eggs (except one) were destroyed. Therefore the school mostly likely closed or changed ownership. Therefore this dessert has been discontinued and is no longer being made.