Soak the bread in the cream. (This is called a panade, which helps to keep the meatloaf juicy.)
Heat your oven to 350˚F.
In the bowl of a standing mixer fitted with the paddle attachment (or in a big bowl if mixing by hand), combine the beef, pork, sausage, salt, pepper, cayenne, nutmeg, rosemary, thyme, sage, parsley, parmesan, and mix on medium, for 20 seconds or so. Then add the bread and cream and the lightly beaten eggs. Continue to mix on medium till it is all well combined.
On a sheet tray, on parchment paper, spread out the meat into a rectangle about an inch thick (see photos below). Put a layer of prosciutto across the entire rectangle. Distribute the spinach evenly across it.
Distribute the chopped egg and provolone over the spinach.
With the long edge of the rectangle closest to you, fold ⅓ of the rectangle over on itself using the parchment to lift it. Pull the parchment back and fold the top third over to enclose the filling and pinch the seams together.
Coat the entire monster with bread crumbs.
Bake until it reaches a temperature of 140˚F to 145˚F. Allow to rest for at least 15 minutes before slicing into slabs and serving. This is excellent cold as well.