Line an 8x8-inch square baking pan with parchment paper or lightly grease it with butter to prepare for the fudge.
In a medium-sized heavy-bottomed saucepan, combine the goat milk, granulated sugar, unsalted butter, and salt. Stir gently to combine before heating.
Place the saucepan over medium heat. Stir continuously until the sugar dissolves and the butter melts completely. Bring the mixture to a gentle boil, then reduce the heat to low.
Continue to cook the mixture, stirring frequently to prevent burning or sticking. Use a candy thermometer to monitor the temperature. The mixture should reach about 235°F (soft ball stage). If you don’t have a thermometer, test by dropping a small amount of the mixture into cold water; it should form a soft, pliable ball.
Remove the pan from heat and let the mixture cool undisturbed for about 10 minutes. Then stir in the vanilla extract.
Using a wooden spoon or a hand mixer on low speed, beat the fudge mixture vigorously until it thickens and loses its glossy sheen. This step is crucial for achieving that creamy, melt-in-your-mouth texture.
If you’re using nuts, fold them gently into the fudge. Pour the mixture into your prepared baking pan, spreading it evenly.
Allow the fudge to cool at room temperature, then refrigerate for at least 2 hours or until firm. Once set, cut into small squares and enjoy!