Bring large pot of water to a boil. Cut the stem from the head of the cabbage deep enough to start a separation of the very outer leaves from the core. Using tongs dip the head in boiling water. This will loosen three or four loosened leaves. Dip again and continue to remove the leaves. You will need to cut the stem as you go, until you have 18 leaves.
Boil the leave about 2 minutes until softened. Place on clean towel.
Put olive oil, onions and mushrooms in large saute pan. Saute until most of the liquid is gone about 10 minute add the garlic and ground turkey cook until turkey is brown and no longer pink.
Remove from heat and add breadcrumbs, salt pepper and parsley mix well.
Spray 9x13 inch casserole with Pam. Put 1/4 cup meat mixture in each cabbage leaf and roll. To roll put the meat mixture at the steam end of the leaf, fold the stem up a little then each side and roll. place in casserole dish seam side down.
mix the remainder of ingredients in bowl and pour over cabbage rolls. Cover with foil.