Heat butter and oil in a Dutch oven over medium-high heat. Rub the roast all over with salt and pepper. Brown the beef on all sides in teh hot butter and oil. It should take about 10 minutes. Pour the Cognac into the pan, warm it, and flame with a match. Pour in the stock and 1/2 cup of the wine. Cover the pan and simmer slowly over low ehat for about 3 hours, adding more wine so that there is always about 1 cup liquid in the pan.

Remove from the heat and let cool to room temperature. Remove the beef and shred into small pieces, following the natural grain of the meat. It should fall apart easily.

Return the shredded beef to the liquid in the pan. Heat until warmed through. Serve as is, sprinkled with parsley, on toast, or as a wonderful base for a cheese steak sandwich.