Preheat the oven to 190ºC . Heat the margarine or water in a medium frying pan over medium heat and cook the onion until transparent, about 5 to 7 minutes. Add the garlic and celery and cook 1 minute longer. Put the mixture in a large bowl with the cashews and Brazil nuts, millet, bread crumbs, potatoes, herbs and spices, lemon juice, and grated rind. Add enough wine, stock, or water to moisten the mixture so it holds together. Season lightly with salt and pepper and mix well. Put half the mixture in a 8- half x 4- 0.5-inch loaf pan. Cover with chestnut puree, then add the remaining loaf mixture. Bake for 45 minutes. If desired, serve with gravy.