01 - Mix creamy peanut butter and powdered sugar in a medium bowl using a fork until mixture reaches crumbly consistency. Reserve for later use.
02 - Distribute half of the prepared peanut butter crumbs evenly across the bottom of the cooled baked pie crust.
03 - Whisk together granulated sugar, all-purpose flour, and salt in a saucepan until thoroughly blended.
04 - Gradually whisk whole milk into dry mixture until smooth. Place saucepan over medium heat, whisking constantly until mixture thickens and begins to boil, approximately 4-5 minutes.
05 - Whisk egg yolks in separate bowl. Gradually incorporate small amount of hot milk mixture into yolks while whisking continuously to temper eggs.
06 - Return tempered egg mixture to saucepan, whisking constantly. Cook additional 2 minutes until filling becomes thick and glossy.
07 - Remove from heat. Stir in unsalted butter and vanilla extract until completely smooth and incorporated.
08 - Pour warm filling over peanut butter crumb layer in crust. Cool 15 minutes at room temperature, then refrigerate minimum 2 hours until completely set.
09 - Beat heavy whipping cream, powdered sugar, and vanilla extract until stiff peaks form. Spread generously over chilled pie surface.
10 - Sprinkle remaining peanut butter crumbs over whipped topping as garnish. Slice and serve chilled.