Combine all ingredients except vanilla. Heat stirring constantly until sugar dissolves and mixture comes to a boiling point. Wipe sugar crystals from sides of pan. Boil to soft ball stage.
(when you drop a few drops into a cup of water, it makes a soft ball.)
Remove from heat and cool slightly. Add vanilla.
Beat with mixer till no longer shiny and mixture begins to hold it's shape. Turn into a buttered pan and quickly spread to sides of pan. Cool and cut into squares. (This can be mixed by hand, but does better if you use a mixer.)