01 - Mix creamy peanut butter and powdered sugar in a medium bowl using a fork until crumbly texture forms. Set aside for later use.
02 - Spread half of the prepared peanut butter crumbs evenly across the bottom of the baked and cooled pie crust.
03 - Whisk together granulated sugar, all-purpose flour, and salt in a saucepan until well blended.
04 - Gradually whisk whole milk into the dry mixture, stirring continuously until smooth and no lumps remain.
05 - Place saucepan over medium heat. Cook while whisking constantly until mixture thickens and begins to boil, approximately 4-5 minutes.
06 - Whisk egg yolks in a separate bowl. Gradually pour small amount of hot milk mixture into yolks while whisking to temper eggs.
07 - Return tempered egg mixture to saucepan, whisking constantly. Cook for 2 additional minutes until filling becomes thick and glossy.
08 - Remove from heat. Stir in unsalted butter and vanilla extract until completely smooth and incorporated.
09 - Pour hot filling over peanut butter crumbs in pie shell. Let cool for 15 minutes at room temperature.
10 - Refrigerate pie for minimum 2 hours until filling is completely set and firm.
11 - Beat heavy whipping cream, powdered sugar, and vanilla extract until stiff peaks form using electric mixer.
12 - Spread whipped cream over chilled pie surface. Sprinkle remaining peanut butter crumbs on top before serving.