Soak the Roman pot (clay cooking pot) in water for 15 minutes, or according to the manufacturer's instructions.
Wash the chicken and pat it dry. Season inside and out with salt and pepper. Drizzle with lemon juice.
Place the chicken in the soaked Roman pot and arrange the smoked bacon slices on top.
In a bowl, mix together the sour cream, red wine, brandy, bay leaf, parsley, thyme, tarragon, and a pinch of grated nutmeg. Pour this mixture into the pot beside the chicken.
Cover the Roman pot with its lid. Place in a cold oven and cook at 240°C (464°F) for 60-70 minutes until the chicken is very tender and reaches 74°C (165°F) internal temperature.
Carefully pour the sauce from the pot into a bowl. Return the uncovered pot to the oven and brown the chicken at 220°C (428°F) for 10 minutes until the skin is golden.
Heat the butter in a pan over medium heat. Cook the sliced mushrooms for 5 minutes until golden and tender. Stir the cooked mushrooms into the reserved sauce.
Season the sauce with salt and pepper to taste. Serve the chicken with the sauce.