Loosen cabbage leaves by putting the whole head into boiling water until the leaves come off. Cut off the hard stem parts, and put the leaves in boiling salted water one at a time until they are partialy cooked. Mix the meat, bread, salt, pepper, egg and onion together. Make a white gravy out of the margarine, flour, water, and milk. Season with salt and pepper and add capers. You can also use tomato sauce for a change. Grease the bottom and sides of a large casserole dish. Layer in the cabbage, meat and gravy alternately. Top with cabbage. Cover and bake at 375F for 45-60 minutes.