Place the milk and cocoa in a saucepan and stir until the milk is boiling, use a whisk to mix them. Remove from the heat after its completely mixed inches.
Beat the egg yolks with the vanilla and sugar until the mixture is pale and smooth, Gradually add the mixture to the chocolate saucepan and simmer it on a medium heat, do not boil the mixture but mix it frequently with the whisk, when the mixture has thickened dissolve the gelatin into 3 tbsp of hot water then mix it into the milk mixture quickly and whisk it again. Place the mix in the fridge until its partially set.
Whisk the egg whites until they hold soft peaks and then fold them into the milk mixture with a wooden spoon gently. Pour the mixture into individual moulds and chill until set, To get them out of the moulds run them under hot water for a few seconds and tap them out.