6 cups sugar
1 cup Hershey's cocoa
1/4 tsp salt
1 (12 oz) can evaporated milk
1 1/2 cup regular milk
1 stick butter
2 tsp vanilla

Butter a 9 x 13 pan. Set aside. Mix cocoa, sugar, and salt in a large, heavy pan. Stir in both milks. Cook over med heat, stirring constantly until mixture comes to full boil. Boil without stirring until mixture reaches a soft ball stage (234°F on candy thermometer). Remove from heat, add vanilla, and butter, but DO NOT STIR. Allow to cool until lukewarm (about 110°F). Beat with wooden spoon until fudge thickens. Spread quickly into buttered pan. Cool completely. Cut into squares.