Heat oven to 350 degrees F. Lightly oil a 9- x 13-inch baking dish. In a large saute pan, over medium high heat, heat the oil and add the chicken skin-side down and cook until deeply-browned; about 4 minutes per side. Remove the chicken to a plate and reserve. Pour off and discard all but 1 tablespoon of the fat in the pan. Lower the heat to medium-low, add the onions and mushrooms, and cook, stirring often until the onions are softened and fragrant; about 10 minutes. Stir in the garlic and ginger and cook until fragrant; about 1 minute. Stir in the hoisin sauce, cranberries, and rice. Transfer the rice mixture to the baking dish and spread into even layer (do not pack it down). Nestle the chicken skin-side up and pour any collected juices over the rice. Pour in the chicken broth. Dot the pan with butter pieces. Cover with foil and bake 45 minutes. Let rest 10 minutes. Remove the foil, fluff the rice, and garnish with scallions.