Beat the Margarine and 100g of Sugar together in a bowl until it becomes light and creamy.
Add the eggs, one at a time, and beat well into the mixture.
Add the flour, 50g of cocoa powder, vanilla essence and milk and fold into the mixture.
Distribute the mixture equally into 4 plastic pudding moulds.
Steam the puddings for one hour.
After 45 minutes, put the milk, 30g of sugar and 30g of cocoa powder into a saucepan and bring to the boil.
Mix the cornflour in a cup with a tbsp of water. Gradually add the cornflour to the chocolate flavoured milk, stirring all the time until it thickens.
When the puddings are ready, serve with the chocolate sauce poured over the top.