Pound the beef top round very thin into a large, even rectangle. Season both sides generously with salt and black pepper.
2
In a mixing bowl, combine the ground pork, grated Parmigiano-Reggiano, grated Pecorino Romano, Pangrattato, finely minced fresh parsley, minced garlic, and the raw egg. Mix thoroughly until all ingredients are well incorporated.
3
Spread the ground pork mixture evenly over the pounded beef top round, leaving a small border around the edges.
