01 - Combine creamy peanut butter and powdered sugar in a medium bowl. Mix with a fork until mixture reaches a crumbly consistency. Reserve for later use.
02 - Distribute half of the prepared peanut butter crumbs evenly across 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 pour whole milk into the saucepan while whisking continuously to create a smooth mixture without lumps.
05 - Place saucepan over medium heat. Cook while whisking constantly until mixture thickens and begins to bubble, approximately 4-5 minutes.
06 - Whisk egg yolks in a separate bowl. Slowly incorporate a small amount of the hot milk mixture into the yolks while whisking briskly to prevent curdling.
07 - Return the egg mixture to the saucepan, whisking continuously. Cook for an additional 2 minutes until filling becomes thick and glossy.
08 - Remove from heat. Stir in unsalted butter and vanilla extract until completely smooth and incorporated.
09 - Pour the warm filling over the peanut butter crumbs in the prepared crust. Let cool at room temperature for 15 minutes, then refrigerate for minimum 2 hours until fully set.
10 - Beat heavy whipping cream, powdered sugar, and vanilla extract with electric mixer until stiff peaks form. Spread whipped cream generously over the chilled pie surface.
11 - Sprinkle remaining peanut butter crumbs over the whipped topping just before serving. Slice and serve chilled.