Instructions
Step 1
Brine the chicken: To a large pot, add the salt, peppercorns, sugar, rosemary, lemon halves and juice, and 2½ quarts of water. Bring to a boil, then turn the heat down to simmer for 30 minutes. Remove from the heat, add 1 cup of ice cubes, and set aside to cool to room temperature. Strain the brine, discarding the solids, then return it to the empty pot; add the chicken and more water as needed to submerge. Cover and refrigerate for at least 12 and up to 24 hours.
Step 2
When you are ready to roast the chicken, position a rack in the center of the oven and preheat to 375°F. Place a wire rack on a rimmed baking sheet. Drain the chicken, discarding the brine, and place on the wire rack, breast-side up. Using paper towels, pat the chicken dry, then set aside at room temperature.
Step 3
Make the stuffing: Grease an 8- by 8-inch baking dish with 1 tablespoon of the butter. Wash and dry the pot, return it to high heat, and add the oil. Once the oil is hot, add the celery, carrots, onion, and garlic and cook, stirring occasionally, until the vegetables begin to soften, 5–7 minutes. Add the half-and-half and stock, season to taste with salt and black pepper, turn the heat to medium-low, and bring to a simmer. Remove from the heat and stir in the bread, followed by half of the cheese. Transfer two-thirds of the stuffing to the baking dish and top with the remaining cheese. To a food processor, add the remaining stuffing and pulse until smooth, adding a bit more stock if the mixture is too dry to process. Using your fingers, separate the chicken skin from the breast, then, using a spoon, pack the puréed stuffing under the skin. Using kitchen twine, tie the legs together, then gently pat the skin all over to evenly distribute the stuffing. Rub the remaining butter all over the skin, then roast the chicken until the skin is golden and a thermometer inserted into the thickest part of the thigh reads 160°F, about 1 hour and 15 minutes. Remove from the oven and set aside to rest for 20 minutes.
Step 4
Meanwhile, bake the remaining stuffing until the cheese has melted, 15–20 minutes. Turn the broiler to high and continue cooking until the cheese is browned and bubbly, 2–4 minutes more. Remove from the oven and set aside.
Step 5
Carve the chicken, carefully removing the stuffed breasts in two whole pieces before slicing. Transfer the meat to a platter and serve hot with the baked stuffing on the side.