A perfect batch of creamy homemade fudge requires precision and innovation: Although the mixture must be heated and cooled and stirred just so, the basic recipe can be flavored almost any which way. You can also get our vanilla fudge variation recipe.
Tip: Successful fudge-making requires heating and cooling the mixture to precise temperatures. Before getting started, check the calibration of your candy thermometer by attaching it to a pan of boiling water; it should register 212 degrees. Leave the thermometer in the boiling water to keep it warm. Letting the mixture cool sufficiently minimizes graininess.
Butter an 8-inch square baking pan; line with parchment paper, allowing a 1-inch overhang. Butter parchment paper, and set aside. Check the calibration of the candy thermometer. Put butter into a large bowl, and set over a wire rack; set aside. Put cream, sugar, chocolate, corn syrup, and salt into a medium heavy saucepan.
Cook over medium-low heat, stirring constantly, until sugar has dissolved and chocolate hasmelted, about 10 minutes. Raise heat to medium. Bring mixture to a boil, washing down sides of pan with a wet pastry brush to prevent sugar crystals from forming. Attach warm thermometer to pan; continue to cook, without stirring, until mixture registers 238 degrees (soft-ball stage), 10 to 15 minutes.
Pour into prepared pan. Using a small offset spatula, quickly spread fudge to sides of pan, and smooth top. Let fudge cool in pan on a wire rack, about 1 hour. Cover with plastic, and refrigerate until completely set, about 8 hours. Run a sharp knife around nonparchment sides to loosen; lift fudge out. Cut into 64 pieces, each 1 inch square. Fudge can be refrigerated between layers of parchment in an airtight container up to 1 week; bring to room temperature before serving.