Put the cream and milk into a saucepan, half the vanilla pod lengthways and scrape the seeds with the point of a knife into the milk mixture and add the pods too then bring to the boil. Meanwhile mix the egg yolks with 70g of the sugar. Whisk the boiled cream mixture on to the egg yolks and sugar and mix well. Return to a clean pan on a low heat and stir every so often, ensuring you stir the bottom and sides of the pan. When the sauce coats the back of a spoon (this should take 3-4 minutes) remove from the heat, give it a good whisk and transfer into a bowl.
Meanwhile you’ll need to whisk the egg whites. Use an electric food mixer with the whisk attachment, or an electric hand whisk (the bowl must be extremely clean with no signs of grease, so rinse with boiling water and dry it first). Whisk the whites with the rest of the caster sugar for 3-4 minutes, until they are really stiff and shiny.
Bring a large pan of water to a simmer and with a large kitchen-serving spoon, lower four spoon shapes of egg white as neatly as you can into the simmering water. Cook for a couple of minutes on each side then transfer to a large plate, preferably lined with kitchen paper to soak up moisture. Cook a couple of batches if your saucepan isn’t big enough.
Serve immediately with the warm sauce, or allow to cool to room temperature. Divide the sauce between four pasta-type bowls and float a cooked meringue in the middle of each.