Chicken Ballotine with Creamy Leek & Chestnut Stuffing

Preheat oven to 350°F. Place bread cubes on a large rimmed baking sheet and bake until dry and toasted, 12 to 15 minutes. Transfer to a large bowl. Increase oven temperature to 400°.

Meanwhile, heat 1 tablespoon each oil and butter in a large skillet over medium-high heat. When the foaming subsides, add leeks, 1/2 teaspoon salt and 1/4 teaspoon pepper. Cook, stirring occasionally and adjusting the heat as necessary, until light golden brown, 8 to 10 minutes. Add 1/4 cup vermouth and cook, stirring, for 1 minute. Add cream and cook until slightly thickened, about 1 minute more. Scrape the mixture into the bowl with the bread. Add chestnuts and herbs and stir to coat.

Place the chicken on a work surface, skin-side down and legs facing downward. Season with 1/2 teaspoon salt and 1/8 teaspoon pepper. Using a small spoon or your fingers, stuff the leg cavities with as much of the bread mixture as will fit. Spread the remaining bread mixture over the surface of the breast meat. Working from the long side of the breast, fold the chicken tightly into the middle. Repeat with the other side, so that it overlaps the other half slightly. Roll and flip the chicken so that the seam is facedown and the skin is faceup.

Starting at the top of the breast, truss the bird, making slipknots by looping kitchen string around and under the chicken repeatedly, at approximately 1-inch intervals. When you reach the bottom, turn the chicken over and thread the twine over and under each of the horizontal strings created during the first step of trussing. Tie the 2 ends of the string together, pulling to tighten and secure. Tuck in any stuffing that has fallen out. Season the outside of the chicken with the remaining 1/2 teaspoon salt and 1/8 teaspoon pepper.

Heat the remaining 1 tablespoon oil in a large ovenproof skillet over medium-high heat. Add the chicken to the pan, seam-side up. Cook, turning occasionally, until browned on all sides, about 10 minutes total. Position the chicken seam-side down and transfer the pan to the oven. Roast until an instant-read thermometer inserted in the center of the stuffing registers 165°F, 40 to 45 minutes.

Transfer the chicken to a clean cutting board and let rest for 10 minutes. Meanwhile, skim fat from the pan drippings. Place the pan over medium heat. Add the remaining 2 tablespoons vermouth and cook, scraping up the browned bits, until the liquid has nearly evaporated, about 3 minutes. Add the remaining 1 tablespoon butter and swirl the pan until it's melted.

Remove string from the chicken and cut into 1/2-inch-thick slices. Serve drizzled with the pan sauce.