Method
Saute the pancetta and scallions together in a pan on medium-low heat until the scallions start to soften and the pancetta fat starts to render. Meanwhile, cook the lima beans in a pot of salted water, boiling water until soft and tender. Using a slotted spoon, transfer half the lima beans to the scallions and pancetta and cook them together on low heat, stirring occasionally (Frozen Lima beans work well too). Transfer the other half of the lima beans to a food processor or high-speed blender. Add one or two ladlefuls of the lima bean cooking water and puree together until smooth. Add the pureed lima beans to the scallion and pancetta mixture and stir together. Cook the spaghetti in a large pot of boiling, salted water until al dente. Use a slotted spoon to transfer the spaghetti to the sauce. Add in ½ cup of the pecorino, 1 to 2 tablespoons of extra virgin olive oil, and freshly ground black pepper. Mix everything together until the spaghetti is well coated. Add pasta water if needed to make creamy Serve warm with grated pecorino Romano on top.