First, make the butterscotch as follows: heat 150g dark brown sugar with 60g butter, stirring until the sugar melts and keep whisking
until the mixture is smooth and homogenized. Continue cooking until it just starts to smoke then remove from the heat and whisk in
250ml double cream, carefully, as it might splutter! Return to a low heat, and continue whisking until smooth. Dissolve 30g cornflour
in 600ml whole milk and beat in 3 egg yolks. Add the hot butterscotch mixture to the milk and eggs and whisk to combine, then pour
everything into a saucepan and bring to a simmer, cooking gently until the mixture thickens and is smooth and creamy. Pour into
glass dishes and cover with clingfilm to prevent a skin forming. Let cool and chill for an hour or more before serving.
Garnish with a blob of whipped cream and some grated chocolate.