Mix the egg yolks with the sugar until creamy until the mixture is thick and light. Add the cornstarch, cocoa and salt and stir in.
Bring the milk to the boil in a saucepan and then add to the egg mixture in the bowl. Stir in and pour back into the pot. Bring the whole thing to the boil with a whisk, stirring, until a thick pudding is formed. Remove from heat, stir in the broken chocolate, butter, vanilla extract and cream.
Fill into dessert bowls and serve warm or cold.
The pudding is sweetened to my liking, you can use less or more sugar, just as you like.