Old-Fashioned Fudge

This is a lot of work, but well worth it. This fudge never lasts past the day I make it.

Original recipe makes 2 dozen pieces

Ingredients

3 tablespoons butter
3 cups white sugar
3 tablespoons cornstarch
1 pinch salt
1 teaspoon distilled white vinegar
1 cup evaporated milk
3 (1 ounce) squares unsweetened chocolate
1 teaspoon vanilla extract

Directions

Butter an 8 or 9 inch square pan. Set aside.
In a large bowl, combine sugar, cornstarch, and salt; mix well. In a heavy saucepan, cook butter or margarine until golden brown; remove from heat. Add sugar mixture; mix well. Stir in vinegar and milk; return to heat. Bring to a boil, stirring frequently. Cover and boil 5 minutes, stirring occasionally.
Stir in chocolate. Insert a candy thermometer and cook, uncovered to soft ball stage, 238 degrees F ( 114 degrees C). Remove from heat; add vanilla and do not stir. Let it sit until pan is lukewarm and easy to hold.
With a sturdy wooden spoon, beat the fudge until it loses is shine.
With buttered hands, quickly press mixture into prepared pan. Let cool slightly before cutting. Keep fudge covered tightly with plastic wrap.