Preheat the oven to 400 degrees F. Season the foie gras with salt and pepper. Place the Foie Gras in a shallow dish and cover with 1/4 cup of the Madeira. Soak the truffle slices in the remaining 1/4 cup of Madeira. Marinate the foie gras and truffles for 10 minutes. Remove the foie gras and truffle slices, reserve the Madeira. In a saute pan, melt 8 tablespoons of butter. Add the potatoes to the melted butter and season with salt and pepper. Saute the potatoes for 3 to 4 minutes. Place the potatoes in the oven and roast the potatoes until golden brown and tender, about 20 minutes, shaking the pan every five minutes. Season the fillets with salt and pepper. In a large saute pan, heat 2 tablespoons of butter. When the butter has melted, add the fillets and sear for 3 to 4 minutes on each side. Remove from the pan. Place the canapes in the saute pan and arrange the fillets on top. Place the pan in the oven and roast for 6 to 8 minutes for medium rare. In a hot saute pan, sear the foie gras for 1 to 2 minutes on each side. Remove the foie gras and drain on a paper-lined plate. Dissolve the arrowroot in 2 tablespoons of the reserved Madeira to form a slurry and set aside. Add the reserved Madeira, truffles and veal stock to the foie gras fat. Bring the liquid up to boil and whisk in the slurry. Boil the liquid for a couple of minutes and then reduce to a simmer. Cook the sauce for 3 to 4 minutes. Season with salt and pepper. To serve, remove the fillets and potatoes from the oven. Place the fillets in the center of each plate. Arrange three potatoes around each fillet. Top each fillet with a piece of seared foie gras. Spoon the sauce over the top of the foie gras and garnish with parsley.