Slice a 1/4 stalk of leek, and a bit of fennel ... very subtle, nice ... experiment, I think you shall enjoy ... Pancetta or bacon or ham adds a tremendous amount of flavor to a Calzone ...
My grandsons like:
eggplant and tomato
Feta, spinach and pancetta or pinenuts
tuna, bell pep, shallot or onion, garlic and spinach beetroot top leaves
salami, provolone or Greek cheese of choice and olives with capers and tomato
It is endless for pizza and calzone, and the figs with goatcheese ! and honey ! Wonderful ...
Best regards, Margi.