How to Make It
In a small saucepan, cook the garlic in the vegetable oil over low heat, turning the cloves, until golden and softened, about 10 minutes. Let the garlic cool in the oil, then drain. Finely chop the garlic; reserve the oil.
In a bowl, combine 3 tablespoons of the chopped roasted garlic with the bread crumbs, 1 1/2 tablespoons of the butter, the preserved lemon rind, parsley and a pinch each of salt and white pepper. Chill the filling until firm.
Boil the Chicken Stock over high heat until reduced to 1 cup. Add the wine, vinegar and 2 tablespoons of the chopped garlic and boil until reduced to 3/4 cup. Season with salt and white pepper. Strain the sauce in a fine sieve, pressing through as much garlic as possible; whisk to incorporate.
Preheat the oven to 400°. Using your fingers, loosen the skin from the chicken breasts. Shape the preserved lemon filling into 4 short ropes and stuff one under the skin of each breast, pressing gently to flatten it. Season the chicken with salt and white pepper.
Heat 2 tablespoons of the reserved garlic oil in a large ovenproof skillet. Add the chicken breasts, skin side down, and cook over high heat until crisp and golden, 5 to 6 minutes. Turn the chicken, transfer the skillet to the oven and roast for about 10 minutes, or until cooked through.
Spoon the Stewed Flageolets with Thyme onto 4 warmed dinner plates and top with the chicken. Pour any accumulated pan juices into the sauce and rewarm. Whisk in the remaining 1 tablespoon of butter. Spoon the sauce over and around the chicken and serve.