Preheat the sous vide cooker to 165° F.
In the same pan used to sear the chicken, add the shallots or onions; sauté for about a minute without browning. Stir in the mushrooms and sauté for several minutes until lightly browned and all of the liquid has evaporated. Pour in the chicken gelatin or broth and Madeira and boil down quickly over high heat until the liquid is syrupy. Stir in the cream and boil down again over high heat until the cream has thickened slightly. Remove from the heat; taste carefully for seasoning. Yield: About 1½ cups.
*Can use Marsala in place of Madeira.