1. Heat oven to 400 degrees . Place chicken pieces on a rimmed baking sheet and drizzle with 1 tbsp of the olive oil, then season with 1 tsp of the salt and 1/8 tsp of the pepper. On a separate rimmed baking sheet, toss mushrooms in remaining 2 tbsp oil, 1/4 tsp of the salt and remaining 1/8 tsp pepper. Roast chicken and mushrooms at 400 degrees for 35 minutes, until golden. Remove mushrooms. Roast chicken 10 minutes more, until cooked.
2. In a large skillet, melt butter over medium heat. Stir in shallots and cook 2 minutes. Stir in flour and cook 1 minute. Whisk in stock, cream and mushrooms. Bring to a boil and cook 3 minutes, until thickened. Stir in thyme, truffle oil, remaining 1/4 tsp salt and, if using, freshly cracked pepper.
3. Place chicken on a platter and pour truffled mushroom sauce over top. If desired, drizzle with additional truffle oil.