Place the chopped chocolate in a heatproof bowl.
Heat the heavy cream in a small saucepan over medium heat until it just begins to simmer, about 3 minutes. Pour over the chocolate and let sit for 2 minutes.
Stir the cream and chocolate together until fully smooth, then stir in the caramel sauce and butter until glossy.
Cover and refrigerate for 2 hours, until firm enough to scoop.
Using a small cookie scoop, portion the mixture into 20 balls and roll briefly between your palms.
Roll each truffle in cocoa powder to coat, then sprinkle with a few flakes of sea salt.
Return to the refrigerator for 15 minutes to firm up before serving.