Spatchcocked Butter-Roasted Lemon and Herb Turkey with Gravy Recipe

Ingredients

• 1 cup salted butter, softened
• 2 tablespoons Dijon mustard
• 1 1/2 tablespoons chopped fresh thyme leaves
• 1 tablespoon fresh lemon juice
• 1 teaspoon grated lemon zest
• 1 teaspoon chopped fresh rosemary
• 1 teaspoon kosher salt, divided, plus more to taste
• 1 teaspoon ground black pepper, divided, or more to taste
• 3 cups coarsely chopped sweet onion
• 2 cups coarsely chopped carrot
• 2 cups coarsely chopped celery
• 1 (12 pound) turkey, thawed if purchased frozen
• 1/2 cup dry white wine
• 2 tablespoons finely chopped shallot
• 1/4 cup all-purpose flour
• 4 1/2 cups chicken stock, or more as needed