01 - Place the chopped dark chocolate in a heatproof bowl.
02 - In a small saucepan, heat the heavy cream over medium heat until just simmering; avoid boiling.
03 - Pour the hot cream over the chopped chocolate and let stand for 1 minute, then gently stir until smooth and fully melted.
04 - Add the butter and stir until completely incorporated and glossy.
05 - Cover the bowl with plastic wrap and refrigerate for 1 to 2 hours until firm but scoopable.
06 - Using a teaspoon or melon baller, scoop small portions of the mixture and quickly roll into balls between your palms.
07 - Roll each truffle evenly in the cocoa powder placed in a shallow dish.
08 - Arrange truffles on a parchment-lined tray and refrigerate for at least 30 minutes before serving.