Chicken Valdostana

Ingredients

Instructions

1. Heat the oven to 400°F with a rack in the lower third. Line a large baking sheet with foil and put it in the oven for 10 minutes. Take it out and toss the squash right on the hot pan with 2 tablespoons oil, ¾ teaspoon salt and ¾ teaspoon pepper. Spread it in a single layer and bake until browned underneath, about 20 minutes. Flip the squash and push it to one side. The hot pan is the trick. It sears the bottoms the second they land.
2. Meanwhile, season the chicken with 1½ teaspoons salt and ½ teaspoon pepper. Put ½ cup flour in a shallow bowl and dredge the chicken until evenly coated, shaking off the extra.
3. Heat 2 tablespoons oil and 1 tablespoon butter in a large skillet over medium. Brown the chicken on both sides without cooking it through, 8 to 12 minutes, then move it to the empty side of the baking sheet. Do not clean the skillet. I'm serious. Top each breast with 2 slices of prosciutto, then the sage leaves, then the Fontina.
4. Back into the oven it all goes. Bake until an instant-read thermometer in the thickest part of the chicken reads 160°F and the squash is tender, 18 to 20 minutes. Rest 5 minutes; the chicken coasts up to 165°F on its own.
5. Meanwhile, heat the remaining 1 tablespoon oil in that gloriously dirty skillet over medium. Add the mushrooms with the remaining ¼ teaspoon salt and ¼ teaspoon pepper and cook, stirring now and then, until browned, about 6 minutes. Stir in the remaining 2 teaspoons flour and cook, stirring constantly, until lightly browned, about 1 minute. Add the wine and scrape up the browned bits until it's reduced by half, about 1 minute. Add the broth and reduce by half again, 3 to 4 minutes. Off the heat, whisk in the remaining 2 tablespoons butter until glossy. Season with salt and pepper.
6. Divide the chicken and squash among plates and spoon the mushroom sauce over the chicken. Sprinkle the squash with flaky salt and scatter sliced sage on top.