"On the other side of the dungeon was a long table, also covered in black velvet. They approached it eagerly but next moment had stopped in their tracks, horrified. The smell was quite disgusting. Large, rotten fish were laid on handsome silver platters; cakes, burned charcoal-black, were heaped on salvers; there was a great maggoty haggis, a slab of cheese covered in furry green mold and, in pride of place, and enormous gray cake in the shape of a tombstone, with tar-like icing forming the words, Sir Nicholas de Mimsy-Porpington Died 31st October, 1492" (Chamber of Secrets 133).
It might be fun for a Halloween party sometime to conjure up a way to make tasty versions of these foul foods, but for now it is Christmas-time, and I'm just as disgusted by these deathly delicacies as Harry, Ron, and Hermione were!