If the fava beans are very small and soft, you can use them raw. If they are medium to large, blanch them until just tender in unsalted boiling water (remove the skins after blanching if they are slightly tough). Smash or finely chop half the beans and leave the other half whole.
Put all the beans into a bowl with the chopped mint (added to taste), olive oil and ricotta. Lightly fork this through, adding the Parmesan, lemon juice and seasoning to taste. Stuff the ravioli with the filling and cook them in gently boiling salted water for around 3 to 4 minutes, until tender. Drain carefully.
Serve drizzled with a little extra olive oil, and scattered with the extra fava beans, some chopped mint, olive oil and some freshly grated or shaved Parmesan.