Line your baking pan with parchment paper, leaving overhang on the sides for easy lifting later.
In a saucepan over low heat, melt the butter gently until it’s just beginning to bubble and smell rich—about 2 minutes. Add the cocoa powder and stir until the mixture becomes shiny and smooth.
Remove the saucepan from heat and stir in the sugar, mixing until well combined and glossy. Add vanilla extract and a pinch of salt, stirring again to incorporate.
Whisk the eggs in a small bowl, then slowly add them to the chocolate mixture, stirring constantly to prevent curdling. The batter should turn thick and shiny, with a slight sheen.
Pour the batter into your prepared pan, spreading it evenly with a spatula. Gently tap the pan on the counter to settle the mixture and release any trapped air bubbles.
Bake in a preheated oven at 180°C (350°F) for 20 to 25 minutes. The edges should be firm and slightly crackled, while the center remains slightly jiggly when gently shaken.
Remove the pan from the oven and let the fudge cool in the pan for at least 30 minutes. Then, lift the fudge out using the parchment overhang and transfer to a wire rack to cool completely.
Once cooled, slice the fudge into squares using a sharp knife wiped with warm water for clean cuts. Serve at room temperature for a soft, chewy texture or slightly warmed for extra gooeyness.
