1. Preheat oven to 350 degrees.
2. Carefully cut the core out of the cabbage and clean away any undesirable leaves, then wash head of cabbage under cold running water.
3. Bring a large pot of fresh water and salt to a boil, then lower whole head of cabbage in, cover the pot, turn heat to a simmer, and cook for 2 to 3 minutes or until the cabbage head softens enough to be able to pull the leaves off individually.
4. Remove cabbage head and let cool on a rack or colander long enough so you can handle it. This recipe will make 18 dinner-sized cabbage rolls, but depending on the size of the leaves, you may have more or less. Take off as many leaves as you can before the difference in size is too great. Sometimes two cabbage heads works better than one in order to get enough similar-sized leaves off the head.
5. After you've removed all the leaves you want, take a small sharp knife and cut a triangle shape along the thick center stem part of each leaf to remove it, making sure you leave the cabbage leaves intact. Set aside.
6. Cut up the cabbage that is leftover and throw it into a large baking dish or Dutch oven.
7. To make filling, put the onion and butter in a large skillet over medium heat and cook until onion is softened; then let cool.
8. In the cooled skillet with onions, crumble up the beef and pork and stir in the garlic, salt, and pepper; mix together but don't overwork it so the meat will stay tender when cooked.
9. Take about 1/2 cup of the meat mixture (more or less depending on the size of the leaf) and put on a cabbage leaf, roll up, tucking in the ends, until the meat is sealed inside the leaf.
10. Put the cabbage roll (seam side down) on top of the chopped cabbage in the baking dish and repeat with all the remaining cabbage leaves, arranging each roll in baking dish. If you don't want to put your cabbage rolls on top of each other, you may have to use two baking dishes if your’s isn't large enough.
11. Pour the beef stock evenly over the cabbage rolls, season to taste with salt and pepper.
Cover and put in preheated oven and bake for 1 hour. This recipe makes 12 to 18 cabbage rolls depending on the size of the leaves you choose.