1
Boil the kettle and heat the milk and cream together either in a saucepan or in a microwave-safe bowl.
2
In a separate saucepan, combine the sugar and cornflour, then sift in the cocoa powder. Pour in the 2 tablespoons of boiling water and whisk until a smooth paste forms.
3
Whisk in the egg yolks, adding one at a time, then incorporate the warmed milk and cream, followed by the vanilla extract.
4
Scrape the sides of the pan and place it over low heat, cook and whisk for approximately 3-4 minutes until the mixture thickens to a consistency resembling mayonnaise.
5
Remove from the heat and whisk in the finely chopped chocolate. Then, pour the mixture into four small cups or glasses, each with a capacity of approximately 150ml/two-thirds of a cup.
6
Place cling film over the tops of the cups or glasses, ensuring it rests on the chocolate surface to prevent the formation of a skin. Refrigerate the cups once they have cooled. Ensure they are not too cold from the fridge when serving. Optionally, top with a dollop of cream.