Place goose in an oiled roasting pan. Season goose, inside and out with salt and pepper. Inside goose, place thyme, rosemary, bay leaves, half a head of garlic and juniper berries. Roast in a preheated 350 degree oven for 1 1/2 to 2 hours, depending on size of goose (14 minutes per pound). During that time, peel and cut the vegetables in cubes of 1 to 1 1/2 inches, and set aside. Baste the goose with its own fat every 10 minutes. 45 minutes before the goose is done, remove the excess fat from the pan and add the vegetables and half a head of garlic.
Roast the bones in a 350 degree oven for 35 minutes. When half done, add the vegetables and roast together. In the last 5 minutes, add the tomato paste. Remove from the oven and transfer to pot and cover with water (or chicken stock if available). De-glaze, with red wine, the pan in which the bones had been roasted, reduce 50 percent and add to the stock. Crush the juniper berries on a cutting board with the bottom of a sauce pot, add to the stock with the thyme, rosemary, bay leaf and garlic, simmer 1 1/2 hours. Strain into a saucepan and reduce gravy to a fine chinois consistency (when it coats the back of a spoon). Finish by whisking in butter, add gin, salt and pepper and reserve in a hot bain marie (double boiler).
Mix all the ingredients, starting with the cream and finishing with diced chestnuts. Butter 8 small dariol molds and divide the mixture between them. Cook in a bain marie (double boiler) in a preheated 325 degree oven for 20 minutes. Cool for a few minutes before un-molding onto the serving platter with the goose and the roast vegetables.