01 - Combine creamy peanut butter and powdered sugar in a medium bowl. Mix with fork until crumbly texture forms. Set aside for later use.
02 - Press half of the prepared peanut butter crumbs evenly into the bottom of the baked and cooled 9-inch 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 constantly until mixture thickens and begins to boil, approximately 4-5 minutes.
05 - Whisk egg yolks in separate bowl. Slowly add small amount of hot milk mixture while whisking continuously to temper eggs and prevent curdling.
06 - Pour tempered egg mixture back into saucepan while whisking. Continue cooking for 2 minutes until thickened and glossy. Remove from heat. Stir in unsalted butter and vanilla extract until smooth and fully incorporated.
07 - Pour warm filling over peanut butter crumb layer in pie shell. Let cool at room temperature for 15 minutes. Refrigerate for minimum 2 hours until completely set.
08 - Beat heavy whipping cream, powdered sugar, and vanilla extract with electric mixer until stiff peaks form. Spread whipped cream generously over chilled pie surface.
09 - Sprinkle remaining peanut butter crumbs over whipped topping. Serve chilled. For enhanced presentation, drizzle with melted chocolate if desired.