Step 1 Pat the chicken thoroughly dry with a paper towel and season generously with salt and pepper on both sides. Have a large braising pan or Dutch oven ready.
Step 2 Heat the oil in a large skillet over medium-high heat. When it’s hot enough that a piece of the chicken dipped in the oil sizzles, add the chicken, skin-side down. You’ll need to do this in two batches.
Step 3Cook until the chicken has browned, 6 to 7 minutes minutes, and then turn and cook on the other side until it no longer looks raw, 5 to 6 minutes. When it is done, remove the chicken to the braising pan and keep it warm.
Step 4Pour off all but 2 tablespoons of oil and add the pancetta. Cook until it is browned, about 3 minutes. Add the onion and cook until it is softened, about 2 minutes, scraping the bottom of the pan to free up any browned sticky bits. Add the carrots and celery and cook until they soften, about 3 minutes. Add the garlic and cook until it is fragrant, about 2 minutes.
Step 5Add the red wine and allow it to reduce by 1/3, until it smells sweet and not of raw alcohol, about 5 minutes. Add the tomatoes, bay leaf and rosemary and cook briefly to marry the flavors. Season to taste with more salt and pepper.
Step 6Pour the sauce over the browned chicken in the braising pan, cover and cook over medium-low heat until the chicken is quite tender and begins to pull away from the bone, 35 to 40 minutes. Sprinkle with parsley before serving.