Preheat oven to 350°. Sprinkle salt and pepper over chicken. Cook 3 chicken leg quarters in 1 Tbsp. hot oil in a large Dutch oven over medium-high heat 5 minutes on each side or until browned. Remove chicken; wipe Dutch oven clean. Repeat with remaining 1 Tbsp. oil and 3 chicken leg quarters.
Cook bacon in Dutch oven over medium heat 4 minutes on each side or until crisp. Remove bacon, and drain on paper towels, reserving 2 Tbsp. drippings in Dutch oven. Sauté mushrooms and next 2 ingredients in drippings over medium-high heat 6 minutes or until browned. Stir in garlic; sauté 1 minute. Stir in tomato paste and 1 cup wine; cook over medium-high heat, stirring often, 2 minutes. Add remaining 2 cups wine, and bring mixture to a boil. Boil, stirring occasionally, about 5 minutes or until reduced by half.
Add chicken and bacon to mushroom mixture in Dutch oven. Add broth and next 3 ingredients; bring mixture to a simmer. Place a piece of parchment paper directly on chicken mixture, and cover Dutch oven with a tight-fitting lid.
Bake at 350° for 1 1/2 hours or until meat pulls away from bone. Let chicken stand in Dutch oven, covered with parchment and lid, at room temperature 30 minutes. Discard parchment paper.
Preheat broiler with oven rack 7 inches from heat. Remove chicken from Dutch oven, reserving vegetables and cooking liquid in Dutch oven. Place chicken on a lightly greased wire rack in a broiler pan.
Broil chicken 2 minutes or until skin is crisp and golden brown. Transfer chicken to a serving platter; cover with aluminum foil. Skim fat from cooking liquid. Discard herb sprigs. Bring cooking liquid to a simmer over medium-high heat, stirring occasionally. Remove from heat. Add butter, and whisk until butter is melted and sauce is smooth. Serve sauce with chicken.