This is another version of authentic sicilian pizza, found in Palermo, which is different from Sfinciuni.
It is a focaccia filled with sliced boiled calf's spleen and tripe with addition of caciocavallo. It is also known as pani cu' la meusa and the best version can be found at Antica Focacceria San Francesco in Palermo (since 1834).
I am not sure is the same thing as "vuasteddra".
According to a sicilian friend of mine, this name refers to a kind of schiacciata/focaccia not too much leavened...
In fact it is at time used in a negative way in bread making "" mi ti vinni na vuasteddra"" as to say that something is not leavened