Peel the potatoes and use a zester to "score" or "rib" the outside of each potato.
Cut the bottom off so that it has a flat surface on which to stand upright. Wrap in aluminum foil and bake until tender in a preheated oven, 350 degrees. This should take about 45 minutes.
Unwrap after baking and allow to cool until it can be handled.
Preheat oven to 400 degrees F.
Cut a cap from the top of the potatoes and scoop out the pulp, leaving enough of a wall to support the stuffing.
Mix the potato pulp with the grated truffles, cream, salt, and pepper.
Place the mixture in a pastry bag and pipe it into the hollowed-out cavity of each potato shell.
Replace the cap and brush the potato with butter. Place the potatoes on a baking sheet and bake for about 20 minutes, or until heated through and golden brown.