01 - Place the chopped chocolate in a medium heatproof bowl.
02 - In a small saucepan, heat the heavy cream over medium heat until just simmering, being careful not to boil.
03 - Pour the hot cream over the chocolate. Let sit for 2 minutes, then gently stir until the chocolate is completely melted and smooth.
04 - Add the butter and vanilla extract, stirring until fully incorporated and the ganache is shiny.
05 - Cover the bowl with plastic wrap and refrigerate for at least 2 hours, or until the ganache is firm enough to scoop.
06 - Using a small melon baller or teaspoon, scoop out portions of the ganache and roll them quickly between your hands to form balls about 1 inch in diameter.
07 - Roll each truffle in cocoa powder to coat, then place on a parchment-lined tray.
08 - Sprinkle each truffle with a pinch of flaky sea salt.
09 - Store in an airtight container in the refrigerator until ready to serve. Bring to room temperature before enjoying for the best flavor and texture.