01 - Mix peanut butter and powdered sugar in a medium bowl using a fork until crumbly texture forms. Reserve mixture for later use.
02 - Distribute half of the prepared peanut butter crumbs evenly across the bottom of the baked pie crust.
03 - Whisk granulated sugar, flour, and salt together in a saucepan until thoroughly blended.
04 - Gradually whisk milk into the dry mixture, stirring continuously until completely smooth and no lumps remain.
05 - Place saucepan over medium heat. Cook while whisking constantly until mixture thickens and just begins to boil, approximately 4 to 5 minutes.
06 - Whisk egg yolks in a separate bowl. Gradually pour small amount of hot milk mixture into yolks while whisking briskly to warm eggs gently.
07 - Return tempered egg mixture to saucepan, whisking continuously. Cook for 2 additional minutes until filling achieves thick, glossy consistency.
08 - Remove from heat immediately. Stir in butter and vanilla extract until fully incorporated and smooth.
09 - Pour warm filling over peanut butter crumb layer in crust. Allow to cool at room temperature for 15 minutes, then refrigerate minimum 2 hours until completely set.
10 - Beat heavy cream, powdered sugar, and vanilla extract together until stiff peaks form. Spread whipped topping generously over chilled pie surface.
11 - Sprinkle remaining peanut butter crumbs over whipped topping just before serving.