Line an 8 or 9-inch square pan with foil butter foil
In heavy 4-quart saucepan stir together sugar cocoa and salt stir in milk and cook over medium heat stirring constantly until mixture comes to full rolling boil without stirring to 234 or until syrup when dropped into very cold water forms a soft ball which flattens when removed from water
Remove from heat
Add butter and vanilla dont stir
Cool at room temperature to 110 lukewarm
Beat with wooden spoon until fudge thickens and loses some of its gloss
Spread quickly into prepared pan cool then cut into squares