Preparation

• Position a rack in the center of the oven and heat the oven to 400°F.

  In a small bowl, mix 1 Tbs. of the balsamic vinegar, 1 Tbs. of the rosemary, the brown sugar, 3/4 tsp. salt, and 1/4 tsp. pepper; stir to dissolve the sugar and salt. Add the olive oil and mix well.

  Scatter the pearl onions over the bottom of a metal, glass, or ceramic baking dish that measures about 10x15x2 inches. Add the mushrooms, cap side up. Stir the vinegar mixture to mix well; spoon 1 Tbs. into a second small bowl and reserve. Use about half of the remaining mixture to brush the mushroom caps. Scatter the pancetta over the mushrooms and onions. Arrange the chicken pieces, skin side up, on top of all, and brush with the remaining vinegar mixture. Roast for 30 minutes.

  Meanwhile, toss the zucchini with the reserved 1 Tbs. of the vinegar mixture. In a measuring cup, combine the wine with the remaining 2 Tbs. balsamic vinegar, 1 tsp. rosemary, and 1/4 teaspoon salt. Remove the roasting pan from the oven and reduce the temperature to 375°F. Pour the wine mixture around the chicken and then scatter the zucchini around the chicken, keeping it toward the edges of the pan as much as possible. Return the pan to the oven and continue to roast until the vegetables are tender and an instant-read thermometer registers 165ºF in several pieces of chicken, 20 to 30 minutes.

  Transfer the chicken to a warmed platter. With a slotted spoon, arrange the vegetables and pancetta around the chicken. Sprinkle the vegetables with a little salt.

  Tilt the roasting pan so that the juices gather in one corner. With a large, shallow spoon, skim as much fat as possible from the pan sauce. Spoon a small amount of sauce over the chicken and vegetables. Put the remaining sauce in a pitcher to pass at the table.