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 - Press half the prepared peanut butter crumbs evenly into the bottom of the baked pie crust, creating a foundation layer.
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 over medium heat, whisking constantly for 4-5 minutes until mixture thickens and begins to boil.
05 - Whisk egg yolks in separate bowl. Slowly incorporate small amount of hot milk mixture while whisking continuously to temper eggs.
06 - Return egg mixture to saucepan, whisking constantly. Cook additional 2 minutes until thick and glossy. Remove from heat and stir in butter and vanilla until smooth.
07 - Pour warm filling over peanut butter crumb layer in pie shell. Cool 15 minutes at room temperature, then refrigerate minimum 2 hours until completely set.
08 - Beat heavy whipping cream, powdered sugar, and vanilla extract until stiff peaks form. Spread generously over chilled pie surface.
09 - Sprinkle remaining peanut butter crumbs over whipped topping as garnish. Slice and serve chilled.