Preheat the oven to 180C/356F/gas mark 4 and grease or line a 9 inch pan with a loose base
Peel the sweet potato and wash to remove any debris.
In another medium sized bowl, use a box grater (the side with the protruding medium holes) to grate the sweet potato followed by the yellow yam.
Place the brown rice flour, cornmeal, cinnamon, nutmeg and coconut sugar into a medium sized bowl then stir and set aside..
Pour the vanilla, browning and coconut milk into the bowl with the sweet potato and stir.
Gradually fold the dry ingredients into the wet ingredients and stir into a smooth batter.
Pour the batter into a spring form baking pan.
Bake for about one hour.
While the pudding is being baked prepare the ingredients for the soft/custard top in a small bowl and whisk.
Remove the sweet potato pudding from the oven then carefully pour the liquid on top, using a spoon to spread evenly over the surface.
Return the pudding to the oven and bake for further 45 minutes to one hour or until the top of the pudding has completely absorbed the coconut milk.
Remove from the oven and allow to completely cool before removing from the baking pan.
Allow the pudding to completely cool before cutting and serving.