In italian it is "zeppola" for the singular and "zeppole" for the plural. We never put an "s" at the end of our words, it is quite easy to remember. Anyway, according to the dictionaries the pronunciation is [zép-po-le] (with the "e" read as in "echo"and the "o" as in "oscar", the stress on the first "e"). Remember the double p sound, it is really important! :P
https://en.wikipedia.org/wiki/Zeppole