01 - Place the chopped chocolate in a heatproof bowl.
02 - In a small saucepan, heat the heavy cream over medium heat until it just begins to simmer. Remove from heat.
03 - Pour the hot cream over the chocolate. Let sit for 2 minutes, then add the butter and vanilla extract.
04 - Stir gently until the chocolate and butter are fully melted and the mixture is smooth and glossy.
05 - Cover the bowl and refrigerate for at least 2 hours, or until the mixture is firm enough to scoop.
06 - Using a teaspoon or melon baller, scoop out small portions and roll them quickly between your palms to form balls (about 1 inch in diameter).
07 - Roll each truffle in the sifted cocoa powder to coat evenly.
08 - Place truffles in a single layer on a parchment-lined tray. Store in the refrigerator until ready to serve.