In a medium saucepan, heat the cream over medium heat until just simmering. Remove from the heat and whisk in the butter until melted.
Pour the hot cream mixture over the chopped chocolate in a bowl and let sit for 5 minutes.
Stir until the chocolate is melted and smooth. Stir in the vanilla extract, if desired. Cover the bowl with plastic wrap and refrigerate for at least 2 hours, or overnight.
When ready to assemble, scoop the truffle mixture by rounded tablespoons and roll into balls. Place the truffles on the prepared baking sheet.
To coat the truffles, either roll them in cocoa powder, sprinkles, crushed nuts, or melted chocolate.
Refrigerate the truffles for at least 30 minutes before serving.