In winter, I like to serve Yukon Gold potatoes, roasted or sautéed in duck fat, and grilled radicchio as a vegetable accompaniment, because it has a strong and pleasantly pungent flavor, which goes well with the chicken. In spring, I offer grilled asparagus.
2. Soak the dried porcini with a pinch of sugar in 2 cups warm water to soften, 2 to 3 hours. Drain the mushrooms, straining the liquid through a coffee filter or paper toweling. Rinse the mushrooms briefly and finely chop. Set aside the mushrooms and soaking liquid separately.
3. In a medium skillet, heat 2 teaspoons of the duck fat over medium-low heat. Add the leek, carrot, and onion; cover and cook until softened, about 5 minutes. Add the porcini mushrooms, fresh and dry sausage, and chopped garlic. Raise the heat to medium and cook, stirring, until caramelized here and there, about 5 minutes. Add the reserved mushroom liquid; raise the heat to high and cook, stirring often, until the liquid is syrupy and glazed, about 5 minutes. Add the chicken broth and simmer until it is absorbed, about 5 minutes longer. Remove from the heat and let cool.
4. Toss the bread with the milk and let soften. Combine the bread paste with the mushroom-sausage mixture and blend well. Add nutmeg and salt and pepper to taste. Pack the stuffing into a 10-inch baking dish greased with duck fat. Cover with foil and refrigerate. (The dressing can be prepared up to 1 day in advance.)
5. About 3 hours before serving, remove the chicken and the dressing from the refrigerator and let stand for 45 minutes. Set an oven rack on the lowest rung and preheat the oven to 375°F.
6. Stir 1 cup water into the dressing. Rub the chicken with duck fat and season generously with salt and pepper. Carefully position the chicken on a vertical roaster with the legs facing up and set in the baking dish above the dressing. Roast in the oven for 30 minutes. Reduce the oven heat to 200°F. and roast for about 1 hour longer, until the internal temperature of the chicken reaches 150° to 155°F.
7. Raise the oven temperature to 400°F and continue roasting until the internal temperature of the chicken reaches 160°F, about 15 minutes longer.
8. Remove the chicken and dressing from the oven. Use oven mitts to carefully lift the chicken off the vertical roaster; cover with foil, and let rest for 20 minutes. Press down on the dressing to express excess fat and discard. Spread the dressing onto a heatproof serving dish and cover with foil.
9. Carve the chicken into 6 or 8 serving pieces. Arrange the chicken pieces over the dressing and return to the oven to reheat, uncovered, to finish cooking, crisping and browning the birds, about 5 minutes. Sprinkle with chopped parsley and the minced garlic and serve at once.
Adam Rapoport, editor in chief of Bon Appetit magazine and the website www.bonappetit.com, knows his way around a grill. He has edited an entire book on the subject: The Grilling Book: The Definitive Guide from Bon Appetit.