In a large bowl, mix together the beef, pork, Parmigiano, eggs, breadcrumbs, parsley, salt, and pepper until well combined.
Flatten the meat mixture onto parchment paper into a square.
Layer the prosciutto cotto and provolone over the top.
Carefully roll it up into a log, sealing it tightly. Dust lightly with flour.
If the polpettone feels too soft, refrigerate for about 20 minutes to firm it up.
Heat olive oil in a large pan (about 12 inches), and sear the polpettone on all sides until golden.
Deglaze the pan with white wine, then add the vegetable broth.
Cover and cook on low heat for about 40 minutes, until tender and juicy.
Slice it up and enjoy!
