Combine sugar, syrup, milk, and salt. Cook over medium heat, stirring constantly, until sugar dissolves and mixture is boiling. Insert candy thermometer. Cook, without stirring to the soft-ball stage, 236 degrees on the candy thermometer.

Remove from heat. Add butter, and let cool until lukewarm without stirring. Add peanut butter and vanilla.

Beat until candy begins to thicken and loses its gloss. Quickly turn into a buttered 8x8 pan, and cool. Cut into squares.

Better if allowed to "cream" for 24 hours.

didn't have a candy thermometer and did the soft ball test by dropping some into a cup of cold water.

This is my absolute favorite fudge of all.....

A trick my old Appalachian granny told me was to let the pan cool after cooking until you could comfortably put your hand on the bottom...then it was ready to beat like crazy.

I'll bet the kitchen aid mixer (wish I had one) would do this task in no time...