In a heavy, medium-size saucepan, combine the cream, vanilla, and salt. Bring to a boil over medium-low heat. Stir in the wine.
Remove from the heat and stir in the chopped chocolate until completely melted. Stir in the butter until it melts and is completely incorporated into the chocolate. Pour into a container, cover, and refrigerate until firm, at least 2 hours.
Line 2 baking sheets with parchment paper. Using a teaspoon or melon baller (dipped in hot water and dried), shape the chocolate into 1-inch balls. Place on the prepared baking sheets. Refrigerate for 10 minutes.
Spread the cocoa powder on a rimmed plate. Roll the truffle balls gently between your hands to shape into smooth round balls. Roll each truffle in cocoa powder. Dust 6 small plates with cocoa powder or confectioners‘ sugar. Arrange 3 or 4 truffles on each plate and serve.