Start by lining an 8x8 inch baking dish with parchment paper, allowing some overhang to make removing the fudge easier once it’s set.

In a medium saucepan, mix together the granulated sugar, cocoa powder, and salt. Set it over medium heat.

Pour in the sweetened condensed milk and add butter. Stir frequently until the mixture is smooth and bubbling, allowing it to cook for 5-7 minutes.

Once the fudge base has thickened, remove it from heat and stir in the fresh lemon juice, lemon zest, and vanilla extract, mixing until fully combined.

Pour the mixture into your prepared baking dish, spreading it evenly with a spatula. Allow the fudge to cool at room temperature for about 30 minutes, then place it in the refrigerator for an additional 1-2 hours to harden completely.

Once set, lift the fudge out of the pan using the parchment paper, slice it into squares, and garnish with extra lemon zest if desired.