In a medium saucepan over medium-high heat boil the wine until reduced by half.
Meanwhile, bring the milk to a boil. Place the chocolate in a small mixing bowl and pour the reduced wine over the top and whisk making sure all of the chocolate is melted. Pour half of the hot milk into the chocolate mixture and whisk to blend.
With the remaining milk, froth with a hand blender or a milk frother.
Pour the chocolate wine mixture into small cups and spoon some of the milk froth over the top, garnish with cocoa powder and serve hot.