01 - Combine creamy peanut butter and powdered sugar in a medium bowl. Mix with a fork until mixture reaches crumbly consistency. Reserve for later use.
02 - Distribute half 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. Cook while whisking continuously until mixture thickens and begins to boil, approximately 4-5 minutes.
05 - Whisk egg yolks in a separate bowl. Slowly incorporate a small amount of the hot milk mixture into yolks while whisking constantly to temper.
06 - Return tempered egg mixture to saucepan, whisking steadily. Continue cooking for 2 minutes until filling achieves thick, glossy consistency.
07 - Remove saucepan from heat. Stir in unsalted butter and vanilla extract until fully incorporated and smooth.
08 - Pour warm filling over peanut butter crumbs in crust. Allow to cool at room temperature for 15 minutes, then refrigerate for minimum 2 hours until completely set.
09 - Beat heavy whipping cream, powdered sugar, and vanilla extract together until stiff peaks form. Spread whipped topping evenly over chilled pie surface.
10 - Sprinkle remaining peanut butter crumbs over whipped cream topping just before serving.