Chop the dark chocolate into small, uniform pieces.

In a saucepan over medium heat, add the heavy cream and unsalted butter. Stir until the mixture is just about to boil.

Pour the hot cream mixture over the chopped chocolate in a bowl and let it sit for one minute.

Stir the mixture gently until smooth, then fold in the orange zest and juice.

Chill the mixture in the refrigerator for 1 to 2 hours until it's firm enough to scoop.

Scoop small portions of the chilled mixture and roll them into balls.

Roll the truffles in cocoa powder or sprinkle with chocolate sprinkles before serving.

Store rolled truffles in an airtight container in the refrigerator.