01 - Combine creamy peanut butter and powdered sugar in a medium bowl. Mix with a fork until mixture reaches crumbly consistency. Set aside for later use.
02 - Distribute half of the prepared peanut butter crumbs evenly across the bottom of the cooled baked pie crust. Press gently to create an even layer.
03 - In a medium saucepan, whisk together granulated sugar, all-purpose flour, and salt until thoroughly blended. Gradually pour in whole milk while whisking continuously to prevent lumps.
04 - Place saucepan over medium heat. Whisk constantly until mixture thickens and reaches a gentle boil, approximately 4 to 5 minutes. Do not stop whisking to prevent scorching.
05 - Whisk egg yolks in a separate heat-proof bowl. Carefully ladle small amounts of the hot milk mixture into yolks while whisking rapidly to temper eggs and prevent curdling.
06 - Return tempered egg mixture to saucepan, whisking constantly. Continue cooking for 2 additional minutes until filling becomes thick and glossy. Remove from heat immediately.
07 - Stir in unsalted butter and vanilla extract until butter melts completely and mixture is smooth and glossy.
08 - Pour warm filling over peanut butter crumb layer in pie shell. Let cool at room temperature for 15 minutes, then refrigerate for minimum 2 hours until completely set.
09 - Beat heavy whipping cream, powdered sugar, and vanilla extract with electric mixer until stiff peaks form. Spread whipped cream evenly over completely chilled pie surface.
10 - Sprinkle remaining peanut butter crumbs generously over whipped cream topping. Serve immediately or refrigerate until ready to serve.