Finely chop the bittersweet chocolate and place 1 pound in a 2-quart mixing bowl.

In a 1-quart saucepan over medium heat, bring the heavy whipping cream to a boil.

Pour the boiling cream into the bowl with the chocolate.

Let the mixture stand for 1 minute.

Stir together with a rubber spatula, whisk, or immersion blender until thoroughly blended.

Blend in the Grand Marnier and the chopped candied orange peel.

Cover the truffle cream and let cool to room temperature.

Chill in the refrigerator until thick but not stiff (2 to 3 hours).

Alternatively, let the truffle cream sit at room temperature for several hours or overnight until completely set and thick.

Line 2 baking sheets with parchment or waxed paper.

Fit a 12-inch pastry bag with a large, plain round pastry tip with a 1/2-inch opening.

Fill the pastry bag partway with the truffle cream.

Holding the pastry bag 1 inch above the paper, pipe out mounds about 1 inch in diameter.

Alternatively, use a small ice cream scoop to form the mounds.

Cover the mounds with plastic wrap and chill in the freezer for 2 hours or in the refrigerator for 6 hours.

Dust your hands with cocoa powder.

Roll the mounds into balls to create the truffle centers.

Cover and chill the centers for another 2 hours in the freezer.

Remove the truffle centers from the freezer and bring to cool room temperature.

Line 2 more baking sheets with parchment or waxed paper.

Melt and temper the remaining 1 1/2 pounds chocolate.

Place a truffle center into the tempered chocolate, coating it completely.

With a dipper or fork, remove the center from the chocolate.

Carefully shake off the excess chocolate.

Turn the truffle out onto the paper.

After dipping 4 truffles, center a sliver of candied orange peel on top of each truffle before the chocolate sets up.

Let the truffles set up at room temperature, or chill them in the refrigerator for 10 to 15 minutes.

When the truffles are set, place them in paper candy cups.

Store in a tightly covered container wrapped in several layers of aluminum foil, the truffles will keep for 1 month in the refrigerator or 2 months in the freezer.

Serve the truffles at room temperature.