Place the sweet potato, coconut milk, milk, double cream and vanilla pod and seeds into a small saucepan and bring to the boil. Simmer until the sweet potato is softened, then remove the vanilla pod and blend the mixture with a hand blender until smooth.
Place one tablespoon of sugar and the egg yolks into a small bowl and whisk until pale and frothy. Pour over the hot blended sweet potato mix and whisk briskly until thickened.
Pour the mixture into a ramekin dish and microwave for two minutes, or until the mixture has just set. Leave to cool for ten minutes.
To serve, sprinkle with the rest of the sugar and use a mini-blowtorch to caramelise the sugar. Dust with icing sugar and serve.
