Preheat the oven to 375F.
2 Lb Italian-style pork sausage (sweet or hot) casings removed
2 Lb Lean Ground Beef
4 cups Fresh Breadcrumbs
2 cups freshly grated Pecorino Romano
3 Eggs lightly beaten
1 cup Whole Milk
Freshly ground black pepper
In a large bowl, combine the sausage, beef, 4 cups of the breadcrumbs, the pecorino, eggs, milk, salt, and pepper. Mix gently but thoroughly with your hands. Cover and refrigerate.
8 quarts water
2 tablespoons salt
1 Lb Baby Spinach (trimmed)
4 Carrots (peeled and cut lengthwise into 3x1/4x1/4 inch batonettes)
12 Scallions (root ends trimmed)
Bring 8 quarts of water to a boil in a large pasta pot. Set up an ice bath nearby.
1/4 Cup All-purpose Flour (plus extra for dusting)
1/4 cup Fresh Breadcrumbs
10 Thin sliced Mortadella (about 5oz)
6 Slice Cacio di Roma (about 4oz)
Add 2 tablespoons salt to the boling water. Dip the spinach leaves in the water just to wilt them, and immediately transfer them to the ice bath; then drain them in a colander. Add the carrots to the boiling water and cook for 10 minutes; then remove with a spider or slotted spoon and set aside. Drop the scallions in the boiling water and cooking for 1 minute; then plunge them in the ice bath and let them cool for 1 minutes. Drain and set on a towel-lined plate.
2 Fresh Rosemary Sprigs
1 cup water
1/2 cup Extra Virgin Olive Oil
Combine the flour with the remaining 1/4 cup breadcrumbs, and heavily dust a wooden board or other work surface with the mixture. On the dusted board, pat the meat mixture into 1 1/2-inch-thick rectangle, about 6 x 16 inches. Place the spinach leaves between two plates and press them together to remove any remaining water, and then lay the spinach over the meat, leaving a 1-inch border on the short sides. Lay the carrot pieces and then the scallions over the spinach, arranging them lengthwise down the rectangle. Lay the mortadella and Cacio di Roma over the scallions. Starting from a long side, roll the meat up like a jelly roll, making it as compact as possible; patch any holes like modeling clay. The roll should be about 16 inches long. Dust the outside with flour.
Place the loaf on a rimmed baking sheet. Press a sprig of rosemary onto each side of the polpettona and pour 1 cup of water into the pan. Drizzle 1/2 cup of the olive oil down the length of the loaf. Bake the polpetton for 1 hour 20 mins, or until it reaches an internal temperature of 165F.
1/4 cup Extra Virgin Olive Oil
Carefully transfer the load to a cutting board and allow it to rest for 15 minutes.
Strain the pan juices into a saucepan and bring to a boil. Season with salt and pepper to taste, add the remaining 1/4 cup oil, and whisk to form a loose sauce.
Slice the meat loaf into 1-inch-thick slices and arrange them on warmed plates. Drizzle with the sauce and serve.