Grease a square tin.
Add the milk and sugar to a pan and slowly bring to the boil, stirring all the time.
Boil steadily till it reaches 116C or soft ball stage.
Remove from the heat and add the butter and vanilla essence.
Leave to cool until luke warm and then stir briskly until it thickens. Add the nuts and stir through.
Pour into the tin and leave to cool. Once it is cool cut it into squares.