Mozarella, parmegian, smoked gouda, and ricotta are required. The fifth is supposed to be gorgonzola...but the wife's allergic to blue cheeses, and I'm still looking for the perfect substitute.
And no, I don't lay the proscuitto out in thin layers. I'm no pro...but I'm not stupid, either.
I'm not worried. After all, you can't even make retatta properly...