I don't think you can, actually! There's lots of places for regular ice cream, though. I believe there is a place close outside the park where you can get it, but I'm not 100% sure where!
I checked the menu data base and the menus for Napoli and Wine Country Trattatori plus a few others. Wine Country has tiramisu but no gelato nor does Napoli. I do not recall seeing gelato on menus except at WDW.