01 - Line an 8x8-inch baking pan with parchment paper, ensuring some overhang for easy removal.
02 - In a medium saucepan over medium heat, melt the butter. Add the peanut butter and stir continuously until fully combined and smooth, about 2 minutes.
03 - Remove the saucepan from heat. Stir in the vanilla extract and salt until evenly incorporated.
04 - Gradually add the sifted powdered sugar, mixing thoroughly after each addition until the mixture is smooth and thick.
05 - Quickly pour the mixture into the prepared pan and spread evenly using a spatula.
06 - Allow the fudge to cool at room temperature for 30 minutes, then refrigerate for at least 1 hour until set.
07 - Lift the fudge from the pan using the parchment overhang and cut into 36 squares. Store in an airtight container at room temperature for up to 1 week or refrigerate for up to 2 weeks.