Prepare the chicken: Cut the 6 chicken leg quarters at the joints to separate the drumsticks and thighs. Trim the pieces to make 6 even portions. Lightly season with salt and black pepper. Add 5 bay leaves, 5 sprigs of thyme, and 3 finely minced garlic cloves. Let the chicken marinate overnight.

Make the broth, part 1: Cut 4 carrots and 2 celery stalks into large pieces. Cut the 2 large red onions into large pieces. Roast the vegetables in the oven at 350°F (180°C) for about 30 minutes. Add the 4 chicken carcasses and roast for another 30 minutes.

Make the broth, part 2: Deglaze the roasting pan with a little water to collect the browned bits. Transfer the vegetables, carcasses, and pan juices to a large pot with water. Add 1 1/4 cups tomato purée (300 ml) and 1/3 cup molasses (100 ml). Add enough water to cover. Simmer gently for about 6 hours to make a rich, reduced broth.

Prepare the chicken: Remove the chicken pieces from the marinade and drain well. Melt duck fat in a skillet. Sear the chicken pieces in the hot fat until well browned. Set the browned chicken aside.

Prepare the garnish: Sauté 7 oz diced bacon or pancetta (200 g) in the skillet with duck fat. Add 9 oz quartered white mushrooms (250 g) and cook until tender. Add 1 yellow onion, diced, and cook until translucent.

Cook the Coq au Vin: Return the chicken pieces to the skillet with the garnish. Pour in 8 1/2 cups red wine (2 liters), enough to cover the chicken. Place the bay leaves and thyme sprigs in a spice ball or cheesecloth and add to the wine. Simmer gently for about 45 minutes.

Prepare the blood thickener: Heat poultry blood to about 180°F (82°C) until it thickens. Gently stir the thickened blood into the sauce without boiling. Let rest for about 5 minutes.

Cook the potatoes: Boil the potatoes in salted water until tender. Keep warm.

Finish the sauce: Remove the chicken pieces from the skillet and set aside. Strain the sauce through a sieve to remove the herbs and vegetables. Boil the sauce over high heat until it reaches the desired consistency.

To serve: Place a chicken thigh and drumstick on each plate. Add potatoes and spoon the sauce over everything.