Preheat oven to 400 degrees F.
Combine the bread crumbs and milk in a large mixing bowl and let sit 5 minutes to rehydrate.
Add the meatloaf mix, egg, bell pepper, zucchini, ½ cup Grana Padano, the scallions, ¼ cup parsley, and the garlic.
Season with 1 ½ teaspoons salt and a generous grinding of black pepper.
Form into 4 (4-inch long) oval meatloaves.
Heat a large cast-iron or ovenproof nonstick skillet over medium heat.
Add the olive oil. When the oil is hot, add the meatloaves and brown all over, about 3 minutes per side.
Pour in the marinara. Cover and bake until bubbling, about 15 minutes.
Uncover, sprinkle with the provolone and the remaining ¼ cup grated cheese, and bake until the meatloaves are crusty and cooked through, about 20 to 25 minutes more.
Sprinkle with the remaining 2 tablespoons parsley and a dusting of grated cheese and serve.