01 - Mix creamy peanut butter and powdered sugar in a medium bowl using a fork until crumbly texture forms. 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 granulated sugar, all-purpose flour, and salt in a saucepan until thoroughly blended.
04 - Gradually whisk whole milk into dry mixture until smooth. Place over medium heat, stirring constantly until mixture thickens and begins to bubble, approximately 4 to 5 minutes.
05 - Whisk egg yolks in separate bowl. Slowly incorporate small amount of hot milk mixture while whisking continuously to prevent curdling.
06 - Return tempered egg mixture to saucepan, whisking constantly. Continue cooking for 2 minutes until mixture achieves thick, glossy consistency.
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 at room temperature for 15 minutes, 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 before slicing and serving.