Blanch the fava beans in boiling water for two minutes, then drain well. (At this point, you may remove the thin “skin.” I didn’t bother and they tasted great and the texture was perfect.) This step may be done in advance. Then, simply refrigerate the beans until you are ready to use.
Cook the spaghetti according to the package directions. Before draining, reserve a half cup of the cooking liquid.
While the pasta is cooking, heat the olive oil in a large skillet (I prefer a cast iron skillet) over medium-high heat. Add the onion and the pancetta and cook until the onion is lightly browned and the pancetta is starting to get crispy, about 8-10 minutes. Add the favas to the onions and pancetta and cook until the beans are tender, about 5 minutes more. Season with a little salt and pepper.
Add the drained pasta, the reserved liquid, the cream, and the greens to the fava mixture. Toss to combine everything well. Check for seasoning, and add salt and pepper to taste.
Garnish with the asiago cheese or pass the cheese at the table.
