Briefly bring half of the cream to the boil in the saucepan with the powdered sugar, stirring every now and then. Take the saucepan off the heat and dissolve the chocolate in it, add the other half of the cream and stir well again.
Now let it cool down a bit, it can be slightly warm, but no longer hot. Now add the vodka and stir everything one last time.
It tastes best when chilled and is drinkable immediately.