Break the chocolate into small pieces and melt with the milk in a saucepan over medium heat. Mix well and bring to the boil.
Whip the cream until stiff (or just use ready-made spray cream). Pour hot chocolate into 4 heat-resistant glasses and pour a large dollop of cream on each. Garnish with marshmallows and chocolate lentils. Serve immediately or the lentils will melt. It is best to add a bar spoon.
Can also be placed in the refrigerator before filling and served cold on hot days.
Variation for adults:
Stir in 2 tablespoons of whiskey and replace the marshmallows with a scoop of ice cream.