In the meantime, prepare your umami gravy. If you’ve spatchcocked your own chicken, cut the reserved backbone into chunks and place them in a cold pan over medium heat to render its fat. If you have opted for the pre-seasoned and spatchcocked chicken, add the chicken/goose fat to a cold pan and turn on to medium heat. Once the fat is hot, add your reserved roughly chopped shallot and 3 peeled and smashed garlic cloves. Cook this for 5min, then deglaze using the brandy and cook the alcohol off for 2min. Add the chicken stock, bay leaf, and dried porcini mushroom. Bring to a boil, then reduce to the lowest heat possible, cover and cook for 10min then cut the heat and strain.