Put the soy milk, cream and sugar in a large saucepan. Slit the vanilla pod lengthways, scrape out the pulp and add to the saucepan with the vanilla pod. Bring to the boil and simmer for about 60-90 minutes.
The dulce de leche is ready when it is nice and brown and viscous. If you put a teaspoon of the mixture on a saucer, it should run down slowly while tilting it slightly.
Put the finished dulce de leche in glasses that have been rinsed with hot water and allow to cool.
I get about half a kilo of spread from the specified amounts.