Rich Cocoa Fudge

1 teaspoon vanilla extract
2/3 cup Hershey's Cocoa or Dutch Processed Cocoa
1/4 cup (1/2 stick) butter
1/8 teaspoon salt
1-1/2 cups milk
3 cups sugar

1. Line 8-or 9-inch square pan with foil, extending foil over edges of pan. Butter foil.

2. Mix sugar, cocoa and salt in heavy 4-quart saucepan; stir in milk. Cook over medium heat, stirring constantly, until mixture comes to full rolling boil. Boil, without stirring, until mixture reaches 234 degrees F. on candy thermometer or until small amount of mixture 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.)

3. Remove from heat. Add butter and vanilla. DO NOT STIR. Cool at room temperature to 110 degrees F. (lukewarm). Beat with wooden spoon until fudge thickens and just begins to lose some of its gloss. Quickly spread into prepared pan; cool completely. Cut into squares. Store in tightly covered container at room temperature. 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 F. (lukewarm). Beat 8 minutes; stir in 1 cup chopped nuts. Pour into prepared pan. (Fudge does not set until poured into pan.)