Reduce heat to medium, and continue to bo9il the mixture without stirring until a small amount of mixture forms a soft ball when dropped into cold water. Remove from heat. Add butter and vanilla. Do not stir allow fudge to cool at room temperature until it reaches 100 degrees. Beat by hand or with portable exlectric mixer until the fudge thickesn and loses some of its gloss.
Quickly pour and spread fudge in lightly buttered 8x8x2 inch pan.
Yield: about 3 dozen squares