Chop 1 oz. hazel nuts. Heat sugar, treacle and milk gently until sugar dissolves. Boil rapidly for about 5 minutes or until a little dropped into cold water forms a soft ball (240°F.). Remove from the heat and add butter and chopped nuts. Cool, stirring occasionally. When mixture is thick, pour into a well greased 8 inch square cake tin. When just set, cut into 1 inch squares and press a whole nut in the centre of each square.