In a large skillet, heat 2 tablespoons of olive oil over medium heat. Add 1 minced red onion, 2 minced carrots, 3 minced celery stalks, and 4 minced garlic cloves. Sauté for 5–7 minutes until the vegetables are soft and fragrant. Stir in ½ cup of chopped parsley, along with a pinch of salt and pepper to enhance the flavors while the sofritto cooks.

In a spacious mixing bowl, combine 2 pounds of ground beef, 1 pound of Italian-style pork sausage, and the sautéed sofritto. Add 1 cup of chopped spinach (if using), 3 cups of Italian-style breadcrumbs, and ¾ cup of whole milk. Gently mix with your hands until just combined, being careful not to overwork the mixture to ensure a tender meatloaf.

Place a large sheet of parchment paper on a clean surface. Transfer the meat mixture onto the parchment and shape it into a rectangle, about 1 inch thick. Layer 12 prepared scallions, 12 slices of Genoa salami, and ½ pound of shredded provolone cheese on top. Carefully roll the meatloaf away from you, sealing the filling inside as you go, creating a cylindrical shape.

Preheat your oven to 350°F (175°C). Lay ½ pound of thick-sliced bacon out in a slightly overlapping row. Place the rolled meatloaf on top and wrap the bacon around it securely, pinching the ends together to maintain shape. This not only adds flavor but also keeps the meatloaf moist during baking.

Transfer the bacon-wrapped meatloaf to a greased baking dish or a lined baking sheet. Bake in the preheated oven for approximately 1 hour or until the internal temperature reaches 160°F (70°C). Look for a golden-brown exterior as a visual cue that it's nearly done.

Once cooked, remove the Hearty Italian Stuffed Meatloaf from the oven and let it rest for about 10 minutes. This crucial step allows the juices to redistribute, making each slice perfectly moist and flavorful when you serve it. After resting, slice and enjoy!