In a large microwave-safe bowl, whisk together the powdered sugar, cocoa powder, and salt until well blended.
Pour in the milk, vanilla extract, and add the butter.
Place the bowl in the microwave and heat on high for 1 minute. Remove and stir the mixture. Microwave for an additional 30 seconds.
Stir vigorously until the fudge is completely smooth and glossy.
Gently fold in the chopped pecans until evenly distributed.
Pour the fudge mixture into your prepared baking dish, spreading it into an even layer.
Refrigerate for at least 1 hour, or until it’s firm. Once set, cut into squares and enjoy!