Start this recipe by heating the oven to 140`c. Cut the oranges into segments and soak in the liqueur for 15 minutes. When ready, divide the orange segments between 4 small dishes. Put the cream and vanilla pod into a saucepan and heat to boiling point. Cover, reduce the heat and allow to infuse for 10 minutes. Meanwhile, whisk the egg yolks and sugar together in a bowl with an electric whisk until thick, pale and creamy. Whisk in the cream and pour over the orange segments in the small dishes. Cook in a large oven dish, half filled with warm water for about 20 minutes, until just set. Leave to chill in the fridge for at least 2-3 hours or overnight. When ready to serve, sprinkle the caster sugar thinly and evenly over each dish and caramelize with a blowtorch (or under a very hot grill), repeat this process until you have golden crackling topping. Serve immediately.