Bring sugar and milk to a boil, stirring constantly.
When boiling, cease stirring and cook gently until a drop forms a soft ball when dropped in cold water
Remove from fire
Add butter and vanilla, cool ten minutes
Beat with electric mixer until creamy, add nuts and spread over cake
NOTE: This is a tricky icing, if it starts to get hard before you spread it, add warm milk by tablespoons until desired consistency for spreading. (it will set up again on cake within a few minutes.