Whisk water and salt in large bowl til salt dissolves. Stir in smashed garlic, thyme sprigs, bay leaves and peppercorns. Add chicken. Cover and chill at least 3 hours or overnight.
Preheat oven to 350. Place whole unpeeled garlic cloves and oil in small ovenproof dish; toss to coat. Cover and roast til tender, about 45 minute Cool slightly and peel.
Meanwhile, place potatoes in med saucepan. Cover with cold water. Boil til tender, about 15 minute Drain and let stand til cool enough to handle. Peel potatoes. (Garlic and potatoes can be prepared 1 day ahead. Cover seperately and chill).
Preheat oven to 400. Cook bacon in heavy large pot over med til brown. Using slotted spoon, transfer bacon to paper towel to drain. Increase heat to med-high. Drain chicken and pat dry. Add chicken, skin side down to bacon drippings in pot. Cook til brown, about 5 min per side. Transfer chicken to rimmed baking sheet. Bake chicken til cooked through, about 25 minute Tent with foil to keep warm.
Return bacon to pot. Stir over med-high heat 30 seconds. Add broth, bring to a boil, scraping up browned bits. Boil til reduced to 2 cups, about 8 minute Add butter; whisk until blended. Stir in parsley, thyme, potatoes, and roasted garlic; stir to warm through. Season with salt and pepper.
Divide potatoes and garlic among plates. Top each with a chicken breast. Drizzle remaining sauce over.