1 . Make 1 cup of coconut water, adding plain water if necessary. Combine in a saucepan the coconut water and sugar; cook, stirring, until syrup reaches the soft ball stage. Remove from the heat and pour in the coconut milk, stirring constantly.
2. Beat the egg yolks lightly. Stir about 1/2 cup of the hot syrup into the eggs, then pour this into the syrup stirring constantly with a wooden spoon. Cook over low heat 5 minutes until the sauce has thickened. Remove from the heat, cool and add the vanilla and rum. Serve over cake, or instead of whipped cream with desserts.