01 - In a medium bowl, combine creamy peanut butter and powdered sugar. Mix with a fork until mixture reaches a crumbly consistency. Set aside for later use.
02 - Distribute half of the prepared peanut butter crumbs evenly across the bottom of the cooled baked pie crust. Press gently to create an even layer.
03 - In a medium saucepan, whisk together granulated sugar, all-purpose flour, and salt until thoroughly combined.
04 - Gradually whisk whole milk into the dry ingredients until smooth and no lumps remain. Place saucepan over medium heat.
05 - Cook mixture over medium heat, whisking constantly to prevent scorching. Continue until mixture thickens noticeably and just begins to bubble, approximately 4 to 5 minutes.
06 - While mixture heats, whisk egg yolks in a separate bowl. Gradually whisk about 1/2 cup of the hot milk mixture into the yolks, stirring constantly to warm eggs gradually without cooking them.
07 - Slowly pour the tempered egg mixture back into the saucepan, whisking continuously. Cook for an additional 2 minutes until filling becomes thick and glossy.
08 - Remove saucepan from heat immediately. Stir in unsalted butter and vanilla extract until butter melts completely and mixture is smooth.
09 - Pour hot filling evenly over the peanut butter crumb layer in pie crust. Let cool at room temperature for 15 minutes, then refrigerate for at least 2 hours until completely set and firm.
10 - In a chilled bowl, beat heavy whipping cream, powdered sugar, and vanilla extract with electric mixer until stiff peaks form and mixture holds its shape.
11 - Spread whipped cream generously over the chilled pie surface. Sprinkle remaining peanut butter crumbs over top as garnish. Serve chilled.