Every time I go in Gaeta, I take a Tiella at "Antico Forno Giordano".
My favorite is the one with octopus but also the tiella with onion is very good.
It is need go or call early because tiella otherwise terminates, the owner does not make it in large quantities. Few but good.
A tiella with octopus for two costs about 8 euro and it is very good