1. In a bowl, blend the cornflour to a smooth paste with a little of the cold milk.
2. Bring the remaining milk to the boil.
3. Pour the boiling milk on to the cornflour mixture, stirring all the time.
4. Pour the mixture back into the saucepan and heat gently, stirring all the time until the mixture thickens and simmers.
5. Allow to simmer for 5 - 10 minutes, stirring occasionally.
6. Remove the pan from the heat and stir in the sugar.
7. Add almond essence to taste, stir well, break the chocolate into squares add to the mixture and stir untill melted.
8. Pour the blancmange into a wetted 1.1 litre (2 pint) mould.
8. Press dampened greaseproof paper or microwave cooking film on to the surface of the blancmange and leave to cool.
9. Chill the cooled blancmange for at least 2 hours, or until set.
10. Unmould the blancmange just before serving.