Cabbage rolls with mushroom sauce

1 onion, chopped
1 clove garlic, crushed (optional)
2 tablespoons butter
3/4 cup uncooked raw rice
1/2 pound ground beef or veal
1/2 pound ground pork
1 teaspoon salt
1/4 teaspoon pepper
1 whole head cabbage (about 3 pounds)
Boiling water
2 cups beef broth or stock
1 can (about 10 ounces) condensed cream of mushroom soup

1. Saute onion and garlic in butter in a large skillet, about 5 minutes. Add rice, meat, salt, and pepper. Stir-fry just to mix well. Remove from heat.
2. Remove core from cabbage. Place whole head in a large kettle filled with boiling water. Cover, cook 3 minutes. Remove softened outer leaves. Repeat until all large leaves are softened and have been removed. Cut thick center stem from each leaf.
3. Taking one large cabbage leaf at a time, spoon about 1 rounded tablespoonful of meat mixture in center of leaf. Cover with a small leaf. Tuck ends up and just over edge of filling; place one end of leaf over filling and roll up loosely. If desired, secure with a wooden pick. Repeat until all filling and leaves are used. Place cabbage rolls in a large casserole; do not make more than 2 layers.
4. Combine beef broth and mushroom soup; Pour over cabbage rolls.
5. Bake at 350 F about 1 1/2 hours.