In a saucepan, heat the cream to a boil. Break the dark chocolate into small pieces and add them to the hot cream until they are completely melted. Let the mixture cool.
Grab a cocktail shaker and fill it with ice cubes. Add the chocolate mixture, 30ml of Ciroc vodka, and 120ml of Baileys into the shaker. Shake vigorously until the contents are well combined.
Pour the mixture into a glass and garnish with marshmallows.