Rubbing truffle butter under the skin takes this simple and beautiful dish to a whole new level—and makes your home smell incredible!
1. Preheat the oven to 425°F. Bring 3 tablespoons of the truffle butter out of the refrigerator to sit at room temperature. Rub 1 tablespoon of the oil over the inside surface of a 12-inch enameled cast iron skillet.
2. Remove the backbone from the chicken: cut lengthwise along each side of the back bone with a sharp knife, discard and open the chicken like a book with the skin side facing down. Use the tip of your knife to score the cartilage that runs down the center, being careful not to cut through it, so that the chicken lies very flat. Season the chicken all over with 3/4 teaspoon of the salt and 1/2 teaspoon of the pepper. Use your fingers to carefully loosen the skin over the breast meat, thighs and legs of the chicken. Gently spread the softened butter under the skin.
3. Heat the oil in the skillet over medium heat. When the oil is hot but not smoking place the chicken skin side down in the skillet. Cook until the underside is browned and no longer sticks to the surface of the skillet, about 10 minutes. Carefully transfer the chicken to a plate, skin side up.
4. Heat the reaming 1 tablespoon oil in the skillet over medium-high; add the mushrooms and remaining 1/2 teaspoon salt and 1/4 teaspoon pepper and cook, stirring occasionally, until the mushrooms brown, about 15-16 minutes. Pour in the wine and cook until evaporated, 4-5 minutes. Pour in the broth, bring to a boil and cook 2 minutes. Place the chicken on top of the mushrooms in the skillet, skin side up. Transfer skillet to the oven and roast until an instant read thermometer inserted into the thickest part of the thigh registers 170°F, about 33-35 minutes.
5. Transfer the chicken to a platter. Whisk the remaining 1 tablespoon (chilled) butter into the mushrooms until melted; stir in the parsley. Spoon mushrooms and sauce over the chicken and top with additional chilled truffle butter if desired.