Heat the cream with the liquorice powder until it reaches around 80 degrees C (bring to a simmer but do not boil). Remove from the heat and leave for 30 minutes.
Beat the egg yolks and the caster sugar together. Mix the egg yolk mixture with the liquorice cream and pour into 4 to 6 ramekins.
Bake in the oven in a bain-marie in a deep roasting tin for about 1 hour in a preheated 100 C / Gas 1/4 oven. Remove and leave to cool.
Sprinkle with brown sugar and caramelise with a blowtorch. If you don't have a blowtorch, you can also pop them under the grill to caramelise the top but you may need to put them back into the fridge for a little while afterwards to cool down before serving.
Serve on plates decorated with liquorice powder or with small liquorice pieces.