Bring a large pot of salted water to boil. Add pasta and cook according to package directions until al dente, a minute before pasta is done add peas.
While pasta cooks, melt 1 tablespoon of butter in a large skillet over medium heat. Add onion and cook for 4 minutes, stirring occasionally. Add Puopolo prosciutto cotto and let it cook until crispy.
Drain pasta and peas, reserving 1 cup of the pasta cooking water. Add pasta and pea to sauce along with ground black pepper. Toss to combine. Adding some of the reserved water if needed. Add Parmiggiano Reggiano just before serving.