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