Place all ingredients except vanilla and butter into a 2 1/2 qt. saucepan

Cook on medium-low until dissolved, stirring constantly

Continue to cook until mixture reaches 238 degrees or soft ball stage

Remove from heat; add butter & sugar

Cool to 110 degrees or until you can hold your hand on bottom of pan

Stir until it begins to lose its gloss and pour into a buttered 3 1/2 x 8" dish (glass if possible)