Adapted from Truffles, Candies, and Confections, by Carole Bloom
3 Tbsp. unsalted butter, softened
2 cups sugar
1/4 cup light corn syrup
3/4 cup half-and-half
Pinch of salt
6 oz. bittersweet chocolate, finely chopped
1 tsp. vanilla extract
Line an 8-inch square pan with aluminum foil that extends over the sides. Coat the foil with 1 tablespoon of the butter. Set aside.
In a 3-quart heavy saucepan over low heat, cook the sugar, corn syrup, half-and-half, and salt until the sugar is dissolved, stirring constantly. Bring the mixture to a boil over medium heat, then brush down the sides of the pan with a pastry brush dipped in warm water to prevent the sugar from crystallizing.
Remove the pan from the heat, and stir in the chocolate in 3 or 4 batches, until completely melted and smooth. Return the pan to medium heat. Place a candy thermometer in the pan, and cook WITHOUT stirring until it registers 238 degrees Fahrenheit on the thermometer. (This may take as long as 20 minutes.)
Remove the pan from the heat, remove the thermometer from the pan, and place the thermometer in warm water to cool. Quickly sprinkle a rimmed baking sheet or a large marble board (at least 14 × 18 inches) with cold water, and immediately pour the hot mixture onto the baking sheet or marble. Do not scrape out the bottom of the pan. Dot the surface of the mixture with the remaining 2 tablespoons butter. Let the mixture cool until it registers 110 degrees Fahrenheit on the thermometer (about 5 to 15 minutes, depending on whether you use a baking sheet or marble).
Scrape the cooled mixture into the bowl of a stand mixer, add the vanilla, and with the paddle attachment, beat the mixture until it thickens and loses its shine (5 to 10 minutes). (Alternatively, you can beat the mixture by hand with a sturdy wooden spoon; it will take longer.) Turn the fudge into the prepared pan. Dampen your hands and use your fingertips to even the top and to press the fudge completely into the corners of the pan. Place the pan on a cooling rack and let it set completely at room temperature (1 to 2 hours).
Remove the fudge from the pan by lifting out the aluminum foil. With a large chef’s knife, cut the fudge evenly into 1-inch squares. Between layers of waxed paper in a tightly covered container, fudge will keep for 10 days at room temperature or 1 month in the refrigerator. Fudge is best served at room temperature.Yield: 64 pieces