Place a large pot of water over high heat and bring to a boil. Add the pasta, salt water and cook to al dente, with a bite.
While the water is coming up to a boil for the pasta, heat a medium, deep skillet over medium heat. Add 1 tablespoon EVOO, 1 turn of the pan, and the butter. When butter melts into the oil, add onions and garlic and season with salt and pepper. Cook, stirring frequently, for 2 minutes then dust the onions with flour and continue to cook for 1 minute. Slowly whisk in milk. Gently bring milk to a bubble, allow the milk to thicken a bit, then stir in the capocola, spinach and 1/2 cup grated Parmigiano. Season sauce with nutmeg and cayenne and remove from the heat. Taste and add a little salt, if you like.
Combine the cooked pasta and the cubed mozzarella with the sauce, stir to coat completely by turning over and over. Transfer dressed pasta to a flameproof baking dish.
To make the breadcrumb topping, combine the breadcrumbs, 2 tablespoons of EVOO and the remaining 1/2 cup Parmigiano. Sprinkle the breadcrumb mixture over the top to cover the pasta from edge to edge. Transfer the baking dish under the broiler and broil until golden brown and crispy. Garnish with chopped parsley. What a gut-buster!