Line 8-or 9-inch square pan with foil; butter foil. In heavy 4-quart saucepan, stir together sugar, cocoa and salt; stir in milk. Cook over medium heat, stirring constantly, until mixture comes to full rolling boil. Boil, without stirring, to 234 degrees Fahrenheit or until syrup, when dropped into very cold water, forms a soft ball which flattens when removed from water. (Bulb of candy thermometer should not rest on bottom of saucepan). Remove from heat. Add butter and vanilla. Do not stir. Cool at room temperature to 110 degrees Fahrenheit (lukewarm). Beat with wooden spoon until fudge thickens and loses some of its gloss. Spread quickly into prepared pan; cool. Cut into squares. About 36 pieces or 1-3/4 pounds. NOTE: For best results, do not double this recipe. Variations: Nutty Rich Cocoa Fudge: Beat cooked fudge as directed. Immediately stir in 1 cup chopped almonds, pecans or walnuts and spread quickly into prepared pan. Marshmallow-Nut Cocoa Fudge: Increase cocoa to 3/4 cup. Cook fudge as directed. Add 1 cup marshmallow creme with butter and vanilla. Do not stir. Cool to 110 degrees Fahrenheit (lukewarm). Beat 8 minutes; stir in 1 cup chopped nuts and pour into prepared pan. (Fudge does not set until poured into pan). High Altitude Directions Increase milk to 1-2/3 cups. Use soft ball cold water test for doneness or test and read thermometer in boiling water, subtract difference from 212 degrees Fahrenheit. Then subtract that number from 234 degrees Fahrenheit. This is the soft ball temperature for your altitude and thermometer. Hersheys is a registered trademark of Hershey Foods Corporation. Recipe may be reprinted courtesy of the Hershey Kitchens. Meal-Master compatible format by: Karen Mintzias