1. Remove and discard root ends and dark green tops of leeks. Cut a slit lengthwise, and rinse thoroughly under cold running water to remove grit and sand. Place leeks in a lightly greased 5- to 6-qt. slow cooker.
2. Cook bacon in a large skillet over medium heat 6 to 8 minutes or until crisp. Remove bacon, and drain on paper towels, reserving 3 Tbsp. hot drippings in skillet. Crumble bacon.
3. Sprinkle roast with pepper and salt. Add olive oil to hot drippings in skillet. Place roast in skillet, and cook over medium-high heat 2 to 3 minutes on each side or until browned. Transfer roast to slow cooker, reserving 1 Tbsp. drippings in skillet.
4. Add garlic to hot drippings, and sauté 30 seconds. Add brown sugar, stirring until sugar melts. Add wine and balsamic vinegar, and cook 2 minutes, stirring to loosen particles from bottom of skillet. Pour mixture over roast, and top with carrots and parsnips.
5. Cover and cook on LOW 8 to 10 hours or until meat shreds easily with a fork.
6. Transfer roast to a cutting board; cut into large chunks, removing any large pieces of fat. Transfer roast and vegetables to a platter, and keep warm.
7. Skim fat from juices in slow cooker, and transfer juices to a 2-qt. saucepan. Add broth, and bring to a boil over medium-high heat. Stir together cornstarch and 2 Tbsp. water in a small bowl until smooth; add to pan, stirring until blended. Boil 1 minute. Add salt and pepper to taste. Serve gravy with roast and vegetables over Creamy Mushroom Grits. Top with crumbled bacon.