01 - Place the finely chopped dark chocolate in a medium heatproof bowl.
02 - Warm the heavy cream in a small saucepan over medium heat until it just begins to simmer; avoid boiling.
03 - Pour the hot cream over the chocolate and let rest undisturbed for 2 minutes, then add the cubed butter and vanilla extract.
04 - Stir gently until the mixture is smooth and glossy with all chocolate and butter melted.
05 - Cover the bowl and refrigerate for approximately 2 hours until the ganache is firm enough to scoop.
06 - Line a baking sheet with parchment paper. Using a small spoon or melon baller, scoop portions of ganache and roll into 1-inch (2.5 cm) balls by hand.
07 - Roll each truffle in cocoa powder or your chosen coating, using gloves or lightly dusting hands with cocoa powder for a clean finish.
08 - Place coated truffles on the baking sheet and refrigerate for at least 15 minutes before serving.