For best results you really have to make these well ahead, ideally the day before, or in the morning if you are planning to serve them in the evening. If you don’t have a cooks blowtorch, you can caramelize the toppings under a very well-preheated, very hot grill.
In a saucepan, heat the cream and milk together to 70°C (touch a little of the mixture to your top lip: if it feels hot but comfortably so, then it’s fine). Add the vanilla and its seeds to infuse, then leave to cool. This should be just enough