Cook pancetta in a large skillet over medium 5 to 7 minutes or until crisp. Drain pancetta on paper towels, reserving drippings in skillet.

Season turkey with salt and pepper. Cook turkey in hot drippings over medium-high 4 minutes on each side or until well browned. Place in a 5- or 6-quart slow cooker.

Add mushrooms and garlic to skillet; cook 8 minutes, stirring occasionally, or until mushrooms are browned. Add carrots, onions, and thyme; cook 5 minutes or until carrots and onions are lightly browned. Add wine to skillet, and cook 1 minute, stirring to loosen any browned bits from bottom of skillet. Pour over turkey in slow cooker; stir in pancetta, bay leaf, and chicken stock.

Cover and cook on LOW for 5 hours or until turkey is very tender and removes easily from the bone.

Transfer turkey and vegetables to a serving platter; keep warm. Pour liquid from slow cooker through a strainer into a measuring cup, and let stand 5 minutes. Skim fat from surface and discard; pour remaining liquid into a medium saucepan. Bring to a boil over medium-high; reduce heat to medium, and simmer 12 minutes or until sauce coats the back of a spoon. Whisk in butter, parsley, and white balsamic vinegar. Season with salt and pepper to taste. Serve turkey and vegetables with sauce.