Hot Cross Buns
Fosbroke says these buns were made of the dough kneaded for the host, and were marked with the cross accordingly. As the Good Friday buns are said to keep for twelve months without turning mouldy, some persons still hang up one or more in their house as a “charm against evil.” (See Cross.)
The round bun represents the full moon, and the cross represents the four quarters of the moon. They were made in honour of Diana by the ancient Roman priests, somewhere about the vernal equinox. Phoenicians, Carthaginians, Egyptians, as well as the Greeks and Romans, worshipped the moon.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894