Getting to the inner fava bean is a double shelling process. First, remove the beans from the pod. Second, steam or blanch the beans, and then cool in an ice bath. The waxy cover of the beans should peel off easily. One pound of fresh favas should yield about a cup.
Prepare the Sauce:
In a large skillet, heat the oil over medium heat and add the onion. Sauté until translucent. Add the pancetta and cook until golden. Add the fava beans and wine. Cover and cook for about 5 more minutes. Add salt and pepper to taste, bearing in mind the saltiness of both the pancetta and the Pecorino. Cover and simmer for about 5-10 minutes, until tender.
In a separate bowl, add the Pecorino and some black pepper. Add a few table spoons of the cooking water and beat together until creamy,
Bring a large pot of salted water to boil. Cook the pasta until 1 minute less then al dente, drain it, retaining about 1 cup of the pasta water. Add the pasta to the fava bean mixture. Cook together for about a minute, adding some of the retained cooking water if it seems dry.