Beef

Bring a large pot of lightly salted water to a boil, add the cabbage head, cover, and cook until leaves are slightly softened; remove and let cool until handleable
Remove 18 whole leaves, cut out any thick center ribs, set whole leaves aside, chop the remainder and spread chopped cabbage in the bottom of a casserole dish
Melt butter in a large skillet over medium-high heat and cook and stir the onion in hot butter until tender, then cool
Stir the cooled onion, ground beef, ground pork, rice, garlic, salt, and black pepper together in a large bowl
Preheat the oven to 350°F.
Place about 1/2 cup of the meat mixture on a cabbage leaf, roll and tuck sides to enclose, repeat with remaining leaves and meat, arrange rolls on top of the chopped cabbage in the dish and season with salt and black pepper
Whisk the tomato puree and pour the tomato mixture over the cabbage rolls, then cover the dish with aluminum foil
Bake in the preheated oven until the cabbage is tender and the meat is cooked through, about 1 hour