Italian Stuffed Meatloaf

I was looking at older recipes and it dawned on me that I needed to make Polpettona Ripiena again. I really enjoyed it the first time around and wanted to do a better job documenting my changes and results.
The finished product is just beautiful, the colors really stand out.

1 pound Italian-style pork sausage (sweet or hot), casing removed
1 pound meatloaf mix (beef, pork and veal) You can use all beef if you can't find it
2 + 1/4 cups fresh breadcrumbs
1 cups Pecorino Romano, freshly grated
2 large eggs
1/2 cup milk
1/2 pound baby spinach
2 carrots, peeled and cut lengthwise into 3 x 1/4 x 1/4 sticks
6 scallions, root ends trimmed
1/4 cup all-purpose flour, plus more for extra dusting
5 thin slices mortadella
6-8 slices of a semi-soft sheep's milk cheese, I used greek Kasseri
1/4 cup extra virgin olive oil

Directions:

Preheat the oven to 400°F.
In a large bowl, combine the sausage, beef, 2 cups of the breadcrumbs, the pecorino, eggs, milk, and salt and pepper. Mix gently but thoroughly with your hands. Cover and refrigerate.

Bring 4 quarts of water to a boil in a large pot. Set up an ice bath nearby. Add 2 tablespoons salt to the boiling water.
Add the carrots to the boiling water and cook for 10 minutes, then remove with a spider or slotted spoon and drop into your ice bath.
Drop the scallions into the boiling water and cook for 1 minute. Add to the ice bath

Combine the flour with the remaining 1/4 cup breadcrumbs, lay out 2 sheets of overlapping wax or parchment paper then spread out the flour and remaining 1/4 cup of breadcrumbs. Press down the meat to make a flat rectangleish shape

Lay the spinach over the meat, leaving a 1-inch border on the sides.

Lay the carrot pieces and then the scallions over the spinach, arranging them lengthwise down the rectangle.
Lay the mortadella and cheese over the scallions.

Starting from a long side, roll the meat up like a jelly roll, use the wax paper as a tool to help keep it tight, make it as compact as possible; patch any holes like modeling clay. Behold the loaf ready for baking.

 
Pour 1 cup of water into the pan. Drizzle 1/4 cup of the olive oil down the length of the loaf.
Bake the loaf for 1 hour, or until it reaches an internal temperature of 165 F.
Carefully transfer the loaf to a cutting board and allow it to rest for 15 minutes.
Slice the meatloaf into 1 inch-thick slices and serve.