Preheat oven to 350°F. Spray a 13x9 inch baking dish with cooking spray. Spread 1/2 (of the 8 oz) can of tomato sauce sauce on bottom of dish. Set aside.
Cabbage: Bring a large pot of water to a boil. Drop the whole head of cabbage into the pot and boil for 5 minutes. Remove from the pot and drain. Allow to cool just enough until it's easy to handle. Use a sharp knife to cut 1/2-1 inch off the stem end. Remove 12 whole outer leaves.
Filling: In a large skillet over medium high heat cook ground beef, ground pork and onion in a drizzle of olive oil. Cook until no pink remains then drain any excess fat from the pan. Remove from the heat.
To the meat add remaining 1/2 (of the 8 oz) can of tomato sauce, 1 Tbsp worcestershire sauce, seasoned salt, granulated garlic, black pepper and smoked paprika. Mix to combine. Add rice and egg, mixing until evenly distributed.
Use a sharp knife to remove the stem from the cabbage leaves. Cut in a V-shape at the root end of each leaf to make it easier to roll. The leaf should be intact.
Assemble: Lay a single cabbage leaf on a cutting board. Place around 1/3 cup meat mixture in center. Bring the sides to the middle then roll ending seam side down. Place side by side in baking dish. Repeat process with remaining leaves.
Sauce: Use the skillet as a mixing bowl. Whisk together the remaining 16 oz tomato sauce, diced tomatoes, 1 Tbsp worcestershire sauce and brown sugar until fully combined. Pour over cabbage rolls.
Cover the pan with foil. Bake for 80-90 minutes until cabbage is tender.
Uncover and let stand 5 minutes then garnish with parsley and serve.