Place the condensed milk, cocoa, vanilla and butter in a pan and mix well.
Place the pan over high heat and cook, stirring all the time.
Cook till a soft ball consistency - a blob of it dropped in a cup of cold water, should set and spread.
Take it off the heat and mix in the walnuts.
Transfer immediately on to the greased plate, level smooth and leave to set. Cut into desired sized pieces when cool.
If you want them shaped into squares or rounds, shape them when cool enough to handle, and set them in a greased plate to set.
Key Ingredients: condensed milk, cocoa powder, vanilla essence, butter, walnuts