Bring 1 cup milk to a boil in a thick bottomed saucepan. In the mean while, whisk together corn starch, cocoa, sugar and salt and stir the mix into 1/2 cup milk at room temperature making sure to avoid dry lumps from forming.

When the milk comes to a boil, reduce heat and stir in the cocoa milk. Let simmer stirring continuously until thick and creamy for about 10-12 mins. It is done when the saucepan bottom can be seen when scraped with a spoon. Remove from heat and stir in the vanilla extract and butter until butter melts and blends in.

Pour into individual serving dishes or bowls of your fancy. To avoid pudding skin from forming, cover with cling wrap on the surface of the pudding (not at the rim of the dish) and let it cool to room temperature. Refrigerate for at least 2 hours or store up to 2 days. Serve cold as is or with suggested garnish.