- With the rack in the middle position, preheat the oven to 200°C (400°F).
- Brush the chicken with the mustard. Season with salt and pepper.
- In an ovenproof skillet over medium-high heat, brown the chicken in the oil. Transfer to a plate and set aside.
- Brown the shallots in the same skillet. Add oil if necessary. Season with salt and pepper. Add the prunes and garlic and cook for 1 minute more. Add the wine. Bring to a boil and reduce until the mixture starts to become syrupy. Add the chicken and the thyme. Bake until the chicken is cooked through, about 10 minutes. Remove the chicken. Add the butter to the sauce and stir until melted. Adjust the seasoning.
- Slice the chicken. Spoon sauce over each serving. Serve with rice and seasonal vegetables.