Preheat the oven to 400 degrees F. Drizzle each piece of puff pastry with the truffle oil. Season with the pepper. Using a truffle slicer, shave the truffle very thin. Spread the shaved truffles over each piece of puff pastry. Sprinkle about 1 tablespoon of the cheese over the truffle slices. Season the asparagus with salt and pepper. Place one spear of the asparagus across the top of the puff pastry, (lengthwise). Roll up the asparagus in the puff pastry like a jelly roll, sealing the ends tightly. Continue the process until all of the asparagus is used. Place the asparagus on a parchment-lined baking sheet. Bake until golden brown, about 6 minutes. In a saute pan, heat the olive oil. Add the shallots. Season with salt and pepper. Saute for 1 minute. Add the garlic. Remove the pan from the heat and add the Cognac. Place the pan back over the heat and flame the Cognac. Shake the pan, constantly until the flame goes out. Add the demi-glace and bring the liquid to a simmer. Stir in the butter and chopped truffles. To serve, ladle the sauce over the asparagus and serve.