Ingredients
Put the sugar and ½ cup of cold water in a small saucepan. Stir over medium heat until sugar dissolves. Increase heat and boil without stirring, to hard-ball stage.
Beat the egg whites in a bowl until stiff and gradually pour in the hot syrup, whisking constantly until the meringue is cold and shiny. Fold in the lucuma puree.
Pour the mixture into a buttered mold and bake in an oven at medium heat for 15 minutes or until puffed and golden. Remove from the oven, allow to cool and unmold on to a serving platter.
While the custard is baking, prepare the vanilla cream. Beat the egg yolks and the sugar in a bowl until the mixture is pale and frothy. Boil the milk in a saucepan, remove from the heat and slowly stir in the egg yolks, mixing constantly. Return the custard to the pan and heat gently. Stir constantly with a wooden spoon without letting it boil, until the custard thickens slightly and coats the spoon with a light film. Remove from the heat and add the vanilla; allow to cool. Serve in a sauceboat together with the custard.