01 - Combine creamy peanut butter and powdered sugar in a medium bowl. Mix with a fork until crumbly texture forms. Set aside for later use.
02 - Distribute half of the prepared peanut butter crumbs evenly across the bottom of the baked and cooled pie crust. Press gently to adhere.
03 - In a saucepan, whisk together granulated sugar, all-purpose flour, and salt until thoroughly blended.
04 - Gradually pour whole milk into the dry ingredients while whisking continuously. Whisk until smooth and no lumps remain.
05 - Place saucepan over medium heat. Cook while whisking constantly until mixture thickens and just begins to boil, approximately 4 to 5 minutes.
06 - Whisk egg yolks in a separate bowl. Gradually whisk in small amount of the hot milk mixture to warm the eggs without cooking them.
07 - Slowly pour tempered egg mixture back into saucepan while whisking constantly. Continue cooking for 2 minutes until filling becomes thick and glossy.
08 - Remove from heat. Stir in unsalted butter and vanilla extract until butter melts completely and mixture is smooth.
09 - Pour hot filling over peanut butter crumbs in pie shell. Let cool at room temperature for 15 minutes, then refrigerate for at least 2 hours until completely set.
10 - Beat heavy whipping cream, powdered sugar, and vanilla extract with electric mixer until stiff peaks form.
11 - Spread whipped cream evenly over chilled pie surface. Sprinkle remaining peanut butter crumbs on top before serving.